Lanner, Ronald M. 1974. A new hybrid from Baja California and the hybrid origin of Pinus quadrifolia. Lanner, Ronald M. 1975. Pinyon pines and junipers of the Southwestern woodlands. Lanner, Ronald M. 1981.
Relict stands of pinyon hybrids in northern Utah.
Great Basin Naturalist. Preliminary classification for the coniferous forest and woodland series of Arizona and New Mexico. U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. Leopold, Aldo. 1924. Grass, brush, timber, and fire in southern Arizona.