Larval key to Genera and selected Species of North American Cocinellidae (Coleoptera)By Rees, B. E., Anderson, D. M., Bouk, D., and Gordon, R. D.
Proceedings of The Entomological Society of Washington, vol. 96(3), pp. 387-412, 1994
"Abstract - An illustrated key to the larvae of 46 of the 60 genera of North American Coccinellidae is presented." (including all genera currently represented in BugGuide) Fourteen genera are not yet understood sufficiently to include.
Paper includes many detailed figures of overall habitus and structures necessary for keys including; head and mouthparts, antennae, body structures and armature types.
The Scymnini (Coleoptera: Coccinellidae) of the United States & Canada: Key to genera and revision of Scymnus, Nephus, & DiomusBy Robert D. Gordon
Bulletin of the Buffalo Society of Natural Sciences, Buffalo, NY, Vol 28, 1976
While Gordon's 1985 work, "The Coccinellidae (Coleoptera) of America North of Mexico" (ref (1)
) does contain keys, illustrations, and distribution maps for all species, for "detailed description and discussion" for Scymnini the reader is referred to this earlier work.
As of 2006, copies were still available from the publisher.
Phylogeny and classification of Cucujoidea and the recognition of a new superfamily Coccinelloidea (Coleoptera: Cucujiformia)By Robertson J.A., Ślipiński A., Moulton M., Shockley F.W., Giorgi A., Lord N.P., McKenna D.D., Tomaszewska W., Forrester J. ...
Syst. Entomol. doi: 10.1111/syen.12138, 2015
Synopsis of adventive species of Coleoptera (Insecta) recorded from Canada. Part 4: Scarabaeoidea... [through Cleroidea]By Klimaszewski J, Langor D, Smith A, Hoebeke E, Davies A, Pelletier G, Douglas HB, Webster RP, Bourdon C, Borowiec L, Scudder GGE
Pensoft Series Faunistica 116: 1-215, 2017
Full title: Synopsis of adventive species of Coleoptera (Insecta) recorded from Canada. Part 4: Scarabaeoidea, Scirtoidea, Buprestoidea, Byrrhoidea, Elateroidea, Derodontoidea, Bostrichoidea, and Cleroidea
Review of the American Corylophidae, Cryptophagidae, Tritomidae and Dermestidae, with other studiesBy T. L. Casey
New York Entomological Society, 1900
Journal of the New York Entomological Society, 8
(2): 51-172, 1900