@article{paperid:201193,
author = {Kayvanfar, Saeed},
title = {the category pme (g,v) and generalized covering groups},
journal = {Journal of Algebra},
year = {2001},
volume = {1},
number = {127},
month = {January},
issn = {0021-8693},
pages = {126--138},
			numpages = {12},
keywords = {covering group - perfect group - variety of groups- category},
}