Biological observations on Ptilothrix sumichrasti (Cresson) and some related groups of Emphorine bees : (Hymenoptera, Anthophoridae) - Linsley, Earle Gorton 1910-2000 (The Academy, 1956)
Separata de: Bulletin of the Southern California Academy of Sciences. Vol. 55, part 2 (January-April 1956)