Hochmuth, R. C., E. H. Simonne, L. L. Davis, and W. L. Laughlin. “Plant Part Selection and Preliminary Sufficiency Ranges for Sap Testing Interpretation of Greenhouse Herbs: HS1123/HS372, 11/2007”. EDIS, vol. 2008, no. 1, Jan. 2008, doi:10.32473/edis-hs372-2007.