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Bobbio, Andrea; Ciancamerla, Ester; Di Blasi, Saverio; Iacomini, Alessandro; Mari, Federico; Melatti, Igor; Minichino, Michele; Scarlatti, Alessandro; Tronci, Enrico; Terruggia, Roberta; Zendri, Emilio |
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Title |
Risk analysis via heterogeneous models of SCADA interconnecting Power Grids and Telco networks |
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Conference Article |
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2009 |
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Proceedings of Fourth International Conference on Risks and Security of Internet and Systems (CRiSIS) |
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90-97 |
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The automation of power grids by means of supervisory control and data acquisition (SCADA) systems has led to an improvement of power grid operations and functionalities but also to pervasive cyber interdependencies between power grids and telecommunication networks. Many power grid services are increasingly depending upon the adequate functionality of SCADA system which in turn strictly depends on the adequate functionality of its communication infrastructure. We propose to tackle the SCADA risk analysis by means of different and heterogeneous modeling techniques and software tools. We demonstrate the applicability of our approach through a case study on an actual SCADA system for an electrical power distribution grid. The modeling techniques we discuss aim at providing a probabilistic dependability analysis, followed by a worst case analysis in presence of malicious attacks and a real-time performance evaluation. |
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Fourth International Conference on Risks and Security of Internet and Systems (CRiSIS) |
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yes |
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Sapienza @ mari @ crisis09 |
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17 |
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Cavaliere, Federico; Mari, Federico; Melatti, Igor; Minei, Giovanni; Salvo, Ivano; Tronci, Enrico; Verzino, Giovanni; Yushtein, Yuri |
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Title |
Model Checking Satellite Operational Procedures |
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Conference Article |
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2011 |
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DAta Systems In Aerospace (DASIA), Org. EuroSpace, Canadian Space Agency, CNES, ESA, EUMETSAT. San Anton, Malta, EuroSpace. |
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We present a model checking approach for the automatic verification of satellite operational procedures (OPs). Building a model for a complex system as a satellite is a hard task. We overcome this obstruction by using a suitable simulator (SIMSAT) for the satellite. Our approach aims at improving OP quality assurance by automatic exhaustive exploration of all possible simulation scenarios. Moreover, our solution decreases OP verification costs by using a model checker (CMurphi) to automatically drive the simulator. We model OPs as user-executed programs observing the simulator telemetries and sending telecommands to the simulator. In order to assess feasibility of our approach we present experimental results on a simple meaningful scenario. Our results show that we can save up to 90% of verification time. |
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yes |
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Sapienza @ mari @ Dasia11 |
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13 |
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Chierichetti, Flavio; Lattanzi, Silvio; Mari, Federico; Panconesi, Alessandro |
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Title |
On Placing Skips Optimally in Expectation |
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2008 |
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Web Search and Web Data Mining (WSDM 2008) |
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15-24 |
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Information Retrieval |
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We study the problem of optimal skip placement in an inverted list. Assuming the query distribution to be known in advance, we formally prove that an optimal skip placement can be computed quite efficiently. Our best algorithm runs in time O(n log n), n being the length of the list. The placement is optimal in the sense that it minimizes the expected time to process a query. Our theoretical results are matched by experiments with a real corpus, showing that substantial savings can be obtained with respect to the tra- ditional skip placement strategy, that of placing consecutive skips, each spanning sqrt(n) many locations. |
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Acm |
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Najork, M.; Broder, A.Z.; Chakrabarti, S. |
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yes |
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Sapienza @ mari @ ChiLatMar08 |
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94 |
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Author |
Coppo, Mario; Dezani-Ciancaglini, Mariangiola; Giovannetti, Elio; Salvo, Ivano |
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Title |
Mobility Types for Mobile Processes in Mobile Ambients |
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Journal Article |
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2003 |
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Electr. Notes Theor. Comput. Sci. |
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78 |
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We present an ambient-like calculus in which the open capability is dropped, and a new form of “lightweight†process mobility is introduced. The calculus comes equipped with a type system that allows the kind of values exchanged in communications and the access and mobility properties of processes to be controlled. A type inference procedure determines the “minimal†requirements to accept a system or a component as well typed. This gives a kind of principal typing. As an expressiveness test, we show that some well known calculi of concurrency and mobility can be encoded in our calculus in a natural way. |
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yes |
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Call Number |
Sapienza @ mari @ Coppo-Dezani-Giovannetti-Salvo:03 |
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74 |
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Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Minichino, Michele; Ciancamerla, Ester; Parisse, Andrea; Tronci, Enrico; Venturini Zilli, Marisa |
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Title |
Automatic Verification of a Turbogas Control System with the Mur$\varphi$ Verifier |
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Conference Article |
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Year |
2003 |
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Hybrid Systems: Computation and Control, 6th International Workshop, HSCC 2003 Prague, Czech Republic, April 3-5, 2003, Proceedings |
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141-155 |
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Automatic analysis of Hybrid Systems poses formidable challenges both from a modeling as well as from a verification point of view. We present a case study on automatic verification of a Turbogas Control System (TCS) using an extended version of the Mur$\varphi$ verifier. TCS is the heart of ICARO, a 2MW Co-generative Electric Power Plant. For large hybrid systems, as TCS is, the modeling effort accounts for a significant part of the whole verification activity. In order to ease our modeling effort we extended the Mur$\varphi$ verifier by importing the C language long double type (finite precision real numbers) into it. We give experimental results on running our extended Mur$\varphi$ on our TCS model. For example using Mur$\varphi$ we were able to compute an admissible range of values for the variation speed of the user demand of electric power to the turbogas. |
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Springer |
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Maler, O.; Pnueli, A. |
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Lecture Notes in Computer Science |
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2623 |
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3-540-00913-2 |
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yes |
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Call Number |
Sapienza @ mari @ Dimmcptz03 |
Serial |
88 |
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Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
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Title |
Finite horizon analysis of Markov Chains with the Mur$\varphi$ verifier |
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Journal Article |
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2006 |
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Int. J. Softw. Tools Technol. Transf. |
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8 |
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4 |
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397-409 |
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In this paper we present an explicit disk-based verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. Given a Markov Chain and an integer k (horizon), our algorithm checks whether the probability of reaching an error state in at most k steps is below a given threshold. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call the resulting probabilistic model checker FHP-Mur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$). We present experimental results comparing FHP-Mur$\varphi$ with (a finite horizon subset of) PRISM, a state-of-the-art symbolic model checker for Markov Chains. Our experimental results show that FHP-Mur$\varphi$ can handle systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems). |
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Springer-Verlag |
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Berlin, Heidelberg |
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1433-2779 |
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yes |
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Call Number |
Sapienza @ mari @ Dimtz06 |
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78 |
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Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
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Title |
Bounded Probabilistic Model Checking with the Mur$\varphi$ Verifier |
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Conference Article |
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2004 |
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Formal Methods in Computer-Aided Design, 5th International Conference, FMCAD 2004, Austin, Texas, USA, November 15-17, 2004, Proceedings |
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214-229 |
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In this paper we present an explicit verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. We restrict ourselves to verification of Bounded PCTL formulas (BPCTL), that is, PCTL formulas in which all Until operators are bounded, possibly with different bounds. This means that we consider only paths (system runs) of bounded length. Given a Markov Chain $\cal M$ and a BPCTL formula Φ, our algorithm checks if Φ is satisfied in $\cal M$. This allows to verify important properties, such as reliability in Discrete Time Hybrid Systems. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call FHP-Mur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$) such extension of the Mur$\varphi$ verifier. We give experimental results comparing FHP-Mur$\varphi$ with (a finite horizon subset of) PRISM, a state-of-the-art symbolic model checker for Markov Chains. Our experimental results show that FHP-Mur$\varphi$ can effectively handle verification of BPCTL formulas for systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems). |
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Springer |
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Hu, A.J.; Martin, A.K. |
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Lecture Notes in Computer Science |
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3312 |
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3-540-23738-0 |
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yes |
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Sapienza @ mari @ Dimtz04 |
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87 |
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Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
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Title |
Exploiting Transition Locality in Automatic Verification of Finite State Concurrent Systems |
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2004 |
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Sttt |
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6 |
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4 |
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320-341 |
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In this paper we show that statistical properties of the transition graph of a system to be verified can be exploited to improve memory or time performances of verification algorithms. We show experimentally that protocols exhibit transition locality. That is, with respect to levels of a breadth-first state space exploration, state transitions tend to be between states belonging to close levels of the transition graph. We support our claim by measuring transition locality for the set of protocols included in the Mur$\varphi$ verifier distribution. We present a cache-based verification algorithm that exploits transition locality to decrease memory usage and a disk-based verification algorithm that exploits transition locality to decrease disk read accesses, thus reducing the time overhead due to disk usage. Both algorithms have been implemented within the Mur$\varphi$ verifier. Our experimental results show that our cache-based algorithm can typically save more than 40% of memory with an average time penalty of about 50% when using (Mur$\varphi$) bit compression and 100% when using bit compression and hash compaction, whereas our disk-based verification algorithm is typically more than ten times faster than a previously proposed disk-based verification algorithm and, even when using 10% of the memory needed to complete verification, it is only between 40 and 530% (300% on average) slower than (RAM) Mur$\varphi$ with enough memory to complete the verification task at hand. Using just 300 MB of memory our disk-based Mur$\varphi$ was able to complete verification of a protocol with about $10^9$ reachable states. This would require more than 5 GB of memory using standard Mur$\varphi$. |
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yes |
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Sapienza @ mari @ DIMTZ04j |
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91 |
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Author |
Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
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Title |
Finite Horizon Analysis of Markov Chains with the Mur$\varphi$ Verifier |
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Conference Article |
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2003 |
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Correct Hardware Design and Verification Methods, 12th IFIP WG 10.5 Advanced Research Working Conference, CHARME 2003, L'Aquila, Italy, October 21-24, 2003, Proceedings |
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394-409 |
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In this paper we present an explicit disk based verification algorithm for Probabilistic Systems defining discrete time/finite state Markov Chains. Given a Markov Chain and an integer k (horizon), our algorithm checks whether the probability of reaching an error state in at most k steps is below a given threshold. We present an implementation of our algorithm within a suitable extension of the Mur$\varphi$ verifier. We call the resulting probabilistic model checker FHP-Mur$\varphi$ (Finite Horizon Probabilistic Mur$\varphi$). We present experimental results comparing FHP-Mur$\varphi$ with (a finite horizon subset of) PRISM, a state-of-the-art symbolic model checker for Markov Chains. Our experimental results show that FHP-Mur$\varphi$ can handle systems that are out of reach for PRISM, namely those involving arithmetic operations on the state variables (e.g. hybrid systems). |
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Springer |
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Geist, D.; Tronci, E. |
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Lecture Notes in Computer Science |
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2860 |
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3-540-20363-X |
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yes |
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Sapienza @ mari @ Dimtz03 |
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84 |
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Della Penna, Giuseppe; Intrigila, Benedetto; Melatti, Igor; Tronci, Enrico; Venturini Zilli, Marisa |
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Integrating RAM and Disk Based Verification within the Mur$\varphi$ Verifier |
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Conference Article |
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2003 |
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Correct Hardware Design and Verification Methods, 12th IFIP WG 10.5 Advanced Research Working Conference, CHARME 2003, L'Aquila, Italy, October 21-24, 2003, Proceedings |
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277-282 |
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We present a verification algorithm that can automatically switch from RAM based verification to disk based verification without discarding the work done during the RAM based verification phase. This avoids having to choose beforehand the proper verification algorithm. Our experimental results show that typically our integrated algorithm is as fast as (sometime faster than) the fastest of the two base (i.e. RAM based and disk based) verification algorithms. |
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Springer |
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Geist, D.; Tronci, E. |
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Lecture Notes in Computer Science |
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2860 |
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3-540-20363-X |
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yes |
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Call Number |
Sapienza @ mari @ DIMTZ03a |
Serial |
85 |
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