Aldrich-Markham, Susan, Oregon State University. Extension Service, Washington State University. Cooperative Extension, University of Idaho. Cooperative Extension System, United States. Department of Agriculture, and Pacific Northwest Cooperative Extension. 1995. The Speedwells : Veronica Hederaefolia L., Veronica Persica Poir., Veronica Filiformis Sm., Veronica Peregrina L. : [Corvallis, Or.] : Oregon State University Extension Service ; [Pullman, Wash.] : Washington State University Cooperative Extension ; [Moscow, Idaho] : University of Idaho Cooperative Extension System ; [Washington, D.C.] : U.S. Dept. of Agriculture.