Particles: Soil, 1972-1976

(1407B) Soil particles, copy, August 9, 1972; (1966B) Micro particles, Grover, Colorado soil, August 6, 1973; (1967B) Soil particles, slide copy, August 10, 1973; (2015B) Grover soil particles, copy, September 14, 1973; (2098B) Eastern Colorado soil particles, November 28, 1973; (2460B) Soil particles, microscopic, copies, July 31, 1974; (2521B) Texas soil particles, copy, August 1974; (2524B) Texas soil particles, August 1974; (2568B) Micro soil particle composite, September 26, 1974; (3006B) Soil particles, composites, electron microscope, microphotos, copy, June 16, 1975; (3489B) Soil particles, two composites, copies, May 20, 1976.