1. Hayfever Plants;Wodehouse,1971
2. Airborne and Allergenic Pollen of North America;Lewis,1983
3. An atlas of airborne pollen grains and common fungus spores of Canada;Bassett,1978
4. Weeds of the West;Whitson,1991
5. Plant Systematics: A Phylogenetic Approach;Judd,1999