Perhaps you should try some spelling variations:
david dang » david ian, david mant, david ng
yang zili » yang dali
2.1 david » 2017 david, 2 david, 210 david
dang hadi » dang hai
wan wang » wen wang, yan wang, wang yang
yang iii » klang iii, zwang iii, yang di
form 2.1 » form 1.1, form 7.2.1, reform 2.1
yang li » yang lin, yang di, yang xi

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: wan wang ((yang iii) OR (((yang zili) OR (yang li)))) form 2.1 david dang hadi ;~.
• Adding a wildcard symbol may retrieve word variants: wan wang ((yang iii) or (((yang zili) or (yang li)))) form 2.1 david dang hadi ;*.