Cresson, E. T. Sr. 1916. The Cresson types of Hymenoptera. Memoirs of the American Entomological Society 1:1-141. PDF

Cresson, E. T. Jr. 1928. The types of Hymenoptera in the Academy of Natural Sciences of Philadelphia other than those of Ezra T. Cresson. Memoirs of the American Entomological Society 5:1-90. PDF