?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=J&rft.au=Xiong%2C+J&rft.aulast=Xiong&rft.date=November+2017&rft.title=CropRef%3A+Reference+Datasets+and+techniques+to+improve+global+cropland+mapping&rft.genre=proceeding