Perhaps you should try some spelling variations:
trinh nghiep » trinh nghien, trinh ghep, trinh nhiet
khanh trinh » hanh trinh, thanh trinh, nhanh tinh
trinh phap » trinh phan, trinh han, trinh chat
trinh nghe » trinh nghien, trinh he, trinh nha
so sach » so sanh, bo sach, co sach
nghe di » nghe vi, nghe dien, nghe dan
tu hoc » te hoc
di hoc » dai hoc, dia hoc, li hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( so sach ((trinh nghiep) or (trinh phap)) tu hoc ) or ( duy khanh trinh nghe di hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( so sach ((trinh nghiep) OR (trinh phap)) tu hoc ) OR ( duy khanh trinh nghe di hoc )).
• Adding a wildcard symbol may retrieve word variants: (( so sach ((trinh nghiep) or (trinh phap)) tu hoc ) or ( duy khanh trinh nghe di hoc ))*.