A new system of soil appraisal in terms of actual and potential productivity (first approximation) /Riquier, Jean Bramao, D.L. /Cornet, Jean-Paul RESSOURCES EN SOL APTITUDE DU SOL EVALUATION CLASSIFICATION CARTOGRAPHIE METHODOLOGIE FAO 1970 text https://www.documentation.ird.fr/hor/fdi:04643 fdi:04643 Riquier Jean, Bramao D.L., Cornet Jean-Paul. A new system of soil appraisal in terms of actual and potential productivity (first approximation). FAO, 1970, 36 multigr. EN