Perhaps you should try some spelling variations:
among letters » among lecturers, among learners, among masters
patients 10.1 » patients 10.12, patients 10.5, patients 10.6
among farmers » salmon farmers
des patients » des patents, les patients, des patienten
yuan zhang » yan zhang, yuan chang, yuan cheng
xuan thang » yuan chang, xiulan zhang
zhang des » zwang des, zugang des, zhang wei

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) OR (xuan thang)) zhang des patients 10.1 ((among letters) OR (among farmers)) ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "meng ((yuan zhang) OR (xuan thang)) zhang des patients 10.1 ((among letters) or (among farmers)) ;~".
• Adding a wildcard symbol may retrieve word variants: meng ((yuan zhang) OR (xuan thang)) zhang des patients 10.1 ((among letters) or (among farmers)) ;*.