Perhaps you should try some spelling variations:
tranh nghiem » trac nghiem, trai nghiem, doanh nghiep
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
trach nhiem » trac nghiem
sach trinh » sach tranh, hanh trinh, sach kinh
nghien tu » nghiep tu, nghien cuu, nghiep vu
co sach » bo sach, cuon sach, hoc sach
tu hoc » te hoc
d hoc » du hoc, ad hoc, de hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( co sach trinh nghien tu hoc ) or ( vu bach ((tranh nghiem) OR (trach nhiem)) d hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( co sach trinh nghien tu hoc ) OR ( vu bach ((tranh nghiem) OR (trach nhiem)) d hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( co sach trinh nghien tu hoc ) or ( vu bach ((tranh nghiem) OR (trach nhiem)) d hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( co sach trinh nghien tu hoc ) or ( vu bach ((tranh nghiem) OR (trach nhiem)) d hoc ))*.