Soil classification handbook : unified soil classification system /

by Howard, Amster K.
Denver, Colo. : Geotechnical Branch, Division of Research and Laboratory Services, Engineering and Research Center, Bureau of Reclamation, 1986
2nd ed.

Handbook of tropical and sub-tropical horticulture /

by Mortensen, Ernest
Washington, D.C. : Dept. of State, Agency for International Development Communications Resources Division, Publications and Technical Services Branch, 1964