Estimating potential evapotranspiration using the Penman procedure :  (Revised and updated) 1991/ 
contributors : Ahmad Jamalludin Shaaban...(et al.) 
 - Kuala Lumpur :  Dept. of Irrigation and Drainage,  1991. 
 - p. :  ill. ; 25 cm. +  1 computer disk. 
 - Hydrological procedure;  no.17 .