1. Abu-Zreig M, Rudra R, Lalonde M, Whitely H, Kaushik N (2004) Experimental investigation of runoff reduction and sediment removal by vegetated filter strips. Hydrological Processes 18:2029–2037
2. Baar L, Matlock RS, Johnson WP, Barron PB (2008) Migration chronology of waterfowl in the Southern High Plains of Texas. Waterbirds 31:394–401
3. Best L, Campa H, Kemp K III, Robel R, Ryan M, Savidge J, Weeks H Jr, Winterstein S (1997) Bird abundance and nesting in CRP fields and cropland in the midwest: a regional approach. Wildlife Society Bulletin 25(4):864–877
4. Beyer HL (2004) Hawth's Analysis Tools for ArcGIS. http://www.spatialecology.com/htools .
5. Birdsall SS, Florin J (1998) Regional Landscapes of the United States and Canada. Accessed online 6/5/09 at http://countrystudies.us/united-states/geography.htm