Perhaps you should try some spelling variations:
taking course » training course, teaching course, taking care
risk taking » risk sharing
course book » course work
wei yang » pei yang, wei wang, wei yang's
dong bin » dong sin, dann bin
book ghi » book i, book ii, book iii
dong di » dong sin
y a » y la

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: ((wei yang) OR (((dong bin) OR (dong di)))) y a risk taking course book ghi ;~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((wei yang) or (((dong bin) OR (dong di)))) y a risk taking course book ghi ;~".
• Adding a wildcard symbol may retrieve word variants: ((wei yang) or (((dong bin) OR (dong di)))) y a risk taking course book ghi ;*.