Combinatorial optimization : algorithms and complexity /

nork Papadimitriou, Christos H.
Argitaratua 1982

Computational complexity /

nork Papadimitriou, Christos H.
Argitaratua 1994

Elements of the theory of computation /

nork Lewis, Harry R., Papadimitriou, Christos H.,
Argitaratua 1981