Perhaps you should try some spelling variations:
class mapping » glass mapping, claims mapping, case mapping
class tapping » glass mapping, class teaching, claims mapping
yan guan » gan guan, yan yuan, yang guang
dong wei » wang wei, dong di, dong hoi
wai yan » wang yan, wei yang
guan li » gan li, yuan li, yuan lin

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

• Performing a fuzzy search may retrieve terms with similar spellings: wai yan guan li ((class mapping) OR (class tapping)) using ((dong sin) or (dong wei)) ;~.
• If you are trying to use Boolean operators, they must be ALL CAPS: wai yan guan li ((class mapping) OR (class tapping)) using ((dong sin) OR (dong wei)) ;*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "wai yan guan li ((class mapping) OR (class tapping)) using ((dong sin) or (dong wei)) ;*".