@inproceedings{Dybvig:guardians,
author = {R. Kent Dybvig and Carl Bruggeman and David Eby},
title = {Guardians in a generation-based garbage collector},
booktitle = {Proceedings of the {SIGPLAN} '93 Conference
                    on Programming Language Design and Implementation},
pages = "207--216",
month = jun,
year = 1993,
texturl = "http://www.cs.indiana.edu/~dyb/pubs/guardians-pldi93.pdf",
annote = {Introduces guardians and describes the implementation of
guardians and weak pairs in Chez Scheme.}}