References
- 1985 . Academic American Encyclopedia s.v. plant; shamrock
- 1976 . American Heritage Dictionary s.v. shillelagh
- 1983 . Encyclopaedia Britannica , 15th ed. s.v. Britain and Ireland, History of; Classification, Biological; Shamrock
- Fernald , M. L. 1950 . Gray' manual of botany , 8th ed. , New York : American Book Company .
- Margulis , L. and Schwartz , K. 1982 . Five kingdoms: An illustrated guide to the phyla of life on earth , San Francisco : W. H. Freeman and Company .
- 1988 . World Book Encyclopedia s.v. Clover; Color; Shamrock