Bulletin of the British Museum (Natural History) Entomology - British Museum (Natural History) (The Museum, 1953)

Catalog of hymenoptera in America north of Mexico - Krombein, Karl V. (Smithsonian Institution Press, 1979)

Catalog of hymenoptera in America north of Mexico - Krombein, Karl V. (Smithsonian Institution Press, 1979)

Hymenoptera of America north of Mexico : synoptic catalog, second supplement - Krombein, Karl V. (U.S. Dept. of Agriculture, 1967)

Hymenoptera of America north of Mexico : synoptic catalog, second supplement - Krombein, Karl V. (U.S. Dept. of Agriculture, 1967)

Hymenoptera of America north of Mexico : synoptic catalog, second supplement - Krombein, Karl V. (U.S. Dept. of Agriculture, 1967)

Hymenoptera of America north of Mexico : synoptic catalog, second supplement - Krombein, Karl V. (U.S. Dept. of Agriculture, 1967)

Hymenoptera of America north of Mexico : synoptic catalog, second supplement - Krombein, Karl V. (U.S. Dept. of Agriculture, 1967)