Perhaps you should try some spelling variations:
patients 10.12 » patients 10.1, patients 14.12, patients 10.3.2
among letters » among lecturers, among learners, among masters
among farmers » salmon farmers
zhang umfang » zhang fang, zhang huafeng, zhang shufang
des patients » des patents, les patients, des patienten
yuan zhang » yan zhang, yuan chang, xuan thang
umfang des » umfang der
meng yuan » meng hsuan, fang yuan, feng juan

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: meng yuan zhang umfang des patients 10.12 ((among letters) OR (among farmers)) ;~.
• Adding a wildcard symbol may retrieve word variants: meng yuan zhang umfang des patients 10.12 ((among letters) or (among farmers)) ;*.