Meadow Observatory H57: Ohio State University Observatory, Lima H58: NASA/MSFC ALaMO, Redstone Arsenal H59: Prairie Grass Observatory, Camp Cullom H60:
New York: Columbia University Press. 1997. ISBN 978-0-231-11013-6. OCLC 37345734. Nilsson MA, Churakov G, Sommer M, Tran NV, Zemann A, Brosius J, Schmitz