author = { Cordts, Steven D. AND Zenner, Guy G. AND Koford, Rolf R. },

title = { Comparison of Helicopter and Ground Counts for Waterfowl in Iowa },

publisher = {The Wildlife Society},

isbn = {0091-7648},

isbn = {1938-5463},

keywords = { Waterfowl and Other Birds },

year = {2002},

url = { http://slubdd.de/katalog?TN_libero_mab2 }