1. Association of Official Agricultural Chemists 1935 Methods of analysis 4th ed. 710 Washington, D. C.
2. Dixon , M. 1934 Manometric methods 100 Cambridge
3. Hatch , A. B. 1937 The physical basis of mycotrophy in Pinus Black Rock Forest Bull. 6
4. The chemical constitution as related to the physical properties of the clays;Marshall;Trans. Ceramic Soc.,1936
5. The relation between mycorrhizae and the development and nutrient absorption of pine seedlings in a prairie nursery;McComb;Jour. For.,1938