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\bibitem[{Della Penna et~al.}(2003){Della Penna, Intrigila, Tronci \& Venturini Zilli}]{DellaPenna_etal2003} Giuseppe Della Penna, Benedetto Intrigila, Enrico Tronci, and Marisa Venturini Zilli. "Synchronized regular expressions." \textit{Acta Inf.} 39, no. 1 (2003): 31--70.

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