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Results found in several dictionaries: Collins, Collaborative Dictionary
enter (up)on  vi +prep obj [career, duties] antreten 
[new era] eintreten in ( +acc ) 
[subject] eingehen auf ( +acc ) 
[transaction] abschließen

Collaborative Dictionary     English-German
'enter (up)on' found in translations in German-English dictionary
! entrance n. to enter  

"Collins German Dictionary, complete & unabridged, 5th edition 2004, © William Collins Sons & Co. Ltd. , 1980 © HarperCollins Publishers 1991, 1997, 1999, 2004"