?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=S+M&rft.au=Virmani%2C+S+M&rft.aulast=Virmani&rft.date=1980&rft.title=Climatic+classification+of+semi-arid+tropics+in+relation+to+farming+systems+research+&rft.genre=proceeding