Kulpa-Eddy, J. A., Taylor, S., Adams, K. M. 2005. USDA perspectives on environmental enrichment for animals. ILAR Journal 46(2), 83-94.

This article provides a brief historical background of the events and circumstances that led to the 1985 Animal Welfare Act (AWA) amendments. It describes the development of the regulations promulgated by the US Department of Agriculture (USDA) in 1991 as a result of these amendments, the reasoning given for the proposals, and the revisions that were made during the process.