For Astragalus
Barneby, R.C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Garden 13: 1-1188.
Isely, D. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States (exclusive of Alaska and Hawaii). Monte L. Bean Life Science Museum, Brigham Young Univ., Provo, UT.