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.
Uwe Schöning. A Low and a High Hierarchy within NP. J. Comput. Syst. Sci., 27(1):14-28, 1983.
Abstract is missing.