The authors and editors of Topics in Endangered Species have identified the following free online resources of information updating the themes explored in the compilation:
US Fish and Wildlife Service Endangered Species Program.
Noah's Options: Initial Cost Estimates of a National System of Habitat Conservation Areas in the United States. Shaffer ML, Casey F, Scott JM. 2002.
Wildlife habitat policy research program, National Council for Science and the Environment.
Publications of Curtis H Flather.
Beyond Reserves and Corridors: Policy Solutions to Facilitate the Movement of Animals and Plants in a Changing Climate. John Kostyack, Joshua J. Lawler, Dale D. Goble, Julian D. Olden, and J. Michael Scott. 2011.