Researchr is a web site for finding, collecting, sharing, and reviewing scientific publications, for researchers by researchers.
Sign up for an account to create a profile with publication list, tag and review your related work, and share bibliographies with your co-authors.
Juris Hartmanis, John E. Hopcroft. What makes Some Language Theory Problems Undecidable. J. Comput. Syst. Sci., 4(4):368-376, 1970.