Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
khach trinh » hanh trinh, kha trinh, thanh trinh
sach trinh » sach tranh, hanh trinh, sach kinh
nghien tu » nghiep tu, nghien cuu, nghiep vu
vu khach » vu khanh, vu khac, vay khach
su sach » so sach, vu sach
tu hoc » te hoc
de hoc » te hoc, du hoc, dien hoc
d hoc » du hoc, ad hoc, y hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach trinh nghien tu hoc ) or ( vu khach trinh nghien ((d hoc) or (de hoc)) ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach trinh nghien tu hoc ) OR ( vu khach trinh nghien ((d hoc) OR (de hoc)) )).
• Adding a wildcard symbol may retrieve word variants: (( su sach trinh nghien tu hoc ) or ( vu khach trinh nghien ((d hoc) or (de hoc)) ))*.