Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Principles of Insect Morphology
By R. E. Snodgrass
McGraw-Hill Book Company, 1935
Cite: 1690688 with citation markup [cite:1690688]
A classic reference work by one of the titans of the subject.

Can be read online at: https://archive.org/details/in.ernet.dli.2015.50045/page/n3