Perhaps you should try some spelling variations:
among actors » among doctors, among acholi, among donors
patients 1 » patients _
yan yang » yang yang, yao yang, dan yang
van den » van der
1 among » 19 among, 1.5 among, 1.8 among
jan de » aan de
van de » van der
wang » wing, wan, lang

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: wang yan yang ((jan de) OR (((van de) OR (van den)))) patients 1 among actors ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wang yan yang ((jan de) or (((van de) OR (van den)))) patients 1 among actors ;~".
• Adding a wildcard symbol may retrieve word variants: wang yan yang ((jan de) or (((van de) OR (van den)))) patients 1 among actors ;*.