The Protozoa - Calkins, Gary N. (Gary Nathan), 1869 -1943 (The Macmillan company, 1901)

Protozoa and other protists - Sleigh, Michael A. (E. Arnold, 1989)

The Protozoa - Calkins, Gary N. (Gary Nathan), 1869 -1943 (Macmillan, 1901)

The Protozoa, by Gary N. Calkins - Calkins, Gary N. (Gary Nathan), 1869 -1943 (Macmillan, 1901)

Protozoa in biological research - Calkins, Gary N. (Gary Nathan), 1869 -1943 (Columbia University Press, 1941)