Some old ones:

Jeffrey Ullman & John Hopcroft: Formal languages and their relation to automata [0]

Ted Codd: A relational model of data for large shared data banks [1]

C.A.R Hoare: Communicating Sequential Processes [2]

[0]http://dl.acm.org/citation.cfm?id=1096945

[1]http://dl.acm.org/citation.cfm?id=362685

[2]http://www.usingcsp.com/cspbook.pdf