@BOOK {CARSKY:2002b, title = {Graphical depiction of cropping calendars for agricultural research: IITA research guide, No. 70}, author = {Carsky, R. and Schulz, S. }, series = {IITA research guide, No. 70}, year = {2002}, publisher = {International Institute of Tropical Agriculture (IITA)}, isbn = {978-131-191-6}, note = {14p.}, }