updated UMD gain & extent citations
updated UMD gain & extent citations

codeminery/gfw,KarlaRenschler/gfw,apercas/gfw,KarlaRenschler/gfw,apercas/gfw,KarlaRenschler/gfw,codeminery/gfw,apercas/gfw,Vizzuality/gfw,codeminery/gfw,apercas/gfw,Vizzuality/gfw,codeminery/gfw,KarlaRenschler/gfw