Hitchcock, C.L; Cronquist, A.; Ownbey, M. 1959. Part 4: Ericaceae through Campanulaceae. In: Hitchcock, C.L.; Cronquist, A; Ownbey, M.; Thompson, J.W. Vascular plants of the Pacific Northwest. Seattle, WA: University of Washington Press: 510 p.

Hitchcock, C.L; Cronquist, A.; Ownbey, M. 1959. Part 4: Ericaceae through Campanulaceae. In: Hitchcock, C.L.; Cronquist, A; Ownbey, M.; Thompson, J.W. Vascular plants of the Pacific Northwest. Seattle, WA: University of Washington Press: 510 p.