1. F. J. Brenner, and F. Artuso , 1981 . Chemical and Biological Characteristics of Agricultural Drainage Tile Outflows . Water Pollution Control Assoc. Magazine, Sept-Oct.:46 -52 .
2. L. Brown, and J. F. Downhower , 1988 . Analysis in Behavioral Ecology . Sinauer Associates, Inc., Sunderland, Massachusetts, 194 pp.