Species Philonix fulvicollis
A synopsis of oak gall wasps (Hymenoptera: Cynipidae) of the southwestern United States ...By James R. Zimmerman
Journal of the Kansas Entomological Society, Vol. 91, No. 1, pp. 58-70, 2018
James R. Zimmerman, A synopsis of oak gall wasps (Hymenoptera: Cynipidae) of the southwestern United States with a key and comments on each of the genera, Journal of the Kansas Entomological Society
(1), 58-70, 2018.
free at JSTOR.
Phylogeny, Evolution and Classification of Gall Wasps: The Plot ThickensBy Ronquist F, Nieves-Aldrey J-L, Buffington ML, Liu Z, Liljeblad J, Nylander JAA
PLoS ONE 10(5): e0123301, 2015
Key to American Insect GallsBy Ephraim Porter Felt
New York State Museum Bulletin, No. 200. , 1917
Freely available at this Google Books link
Although quite old, and likely with much out-of-date nomenclature...this reference has a large number of useful line drawings and photos (including 16 plates w/ 9 photos each = 144 photos at the end). The name of this work is rather misleading...as there's no "key" per se. Instead, the galls are organized by plant families of their hosts, listed there with (usually very) brief comments on rearing records, perhaps some minimal descriptive info, and abbreviated bibliographic references.