Weaver chair, R. W., Angle, S., Bottomley, P., Bezdicek, D., Smith, S., & Tabatabai, A. (1994). Methods of soil analysis. Part 2: Microbiologicaland biochemical properties. Wisconsin, Estados Unidos de América: Soil Science Society of America, Inc..

Weaver chair, R. W.,, Scott Angle, Peter Bottomley, David Bezdicek, Scott Smith, and Ali Tabatabai. Methods of Soil Analysis. Part 2: Microbiologicaland Biochemical Properties. Wisconsin, Estados Unidos de América: Soil Science Society of America, Inc., 1994.

Weaver chair, R. W.,, et al. Methods of Soil Analysis. Part 2: Microbiologicaland Biochemical Properties. Wisconsin, Estados Unidos de América: Soil Science Society of America, Inc., 1994.