References
- Dahnke , W. C. , ed. 1988 . Recommended Chemical Soil Test Procedures for the North Central Region , Bulletin No. 499 Fargo , ND : North Dakota Agricultural Experiment Station, North Dakota State University . (Revised)
- Donohue , S. T. , ed. 1992 . Reference Soil and Media Diagnostic Procedures for the Southern Region of the United States , Southern Cooperative Series Bulletin Blacksburg , VA : VPI .
- Garfield , F. M. 1991 . Quality Assurance Principles for Analytical Laboratories , Arlington , VA : AOAC International . 2200 Wilson Blvd., Suite 400
- Gavlak , R. G , Horneck , D. A. and Miller , R. O. , eds. 1994 . Plant, Soil and Water Reference Methods for the Western Region , A Western Regional Extension Publication . WREP 125
- Reference Soil Test Methods for the Southern Region of the United States. 1983
- Sims , J. T. and Wolf , A. M. , eds. 1991 . Recommended Soil Testing Procedures for the Northeastern United States , Bulletin #493 Newark , DE : Agricultural Experiment Station, University of Delaware .
- Soil and Plant Analysis Council, Inc. 1992 . Handbook on Reference Methods for Soil Analysis , Athens , GA : Georgia University Station .
- Reference Soil Test Methods for the Southern Region of the United States , Southern Cooperative Series Bulletin 289 Athens , GA : University of Georgia College of Agriculture and Experiment Station .
- Taylor , J. K. 1987 . Quality Assurance of Chemical Measurements , N.W. Boca Raton , FL : Lewis Publishers, Inc., CRC Press . 2000 Corporate Blvd.
- Wolf , A.M. and Beegle , D.B. 1991 . “ Recommended Soil Tests for Macronutrients: Phosphorus, Potassium, Calcium and Magnesium ” . In Recommended Soil Testing Procedures for the Northeastern States , Northeast Regional Publication Bulletin #493 Newark , DE : Agricultural Experiment Station, University of Delaware .
- Agricultural Analytical Services Laboratory, The Pennsylvania State University, University Park, PA, 16802–1100.