Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
tranh nghiem » trac nghiem, trach nhiem, trai nghiem
bach tranh » sach tranh, canh tranh, bac thanh
cuon sach » duong sach, cuoc cach, nuoc sach
nghien tu » nghiep tu, nghien cuu, nghiep vu
nghiem d » nghiem de, nghiem do, nghiem _
co sach » bo 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) OR (cuon sach)) trinh nghien tu hoc ) or ( vu bach tranh nghiem d hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((co sach) OR (cuon sach)) trinh nghien tu hoc ) OR ( vu bach tranh nghiem d hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( ((co sach) OR (cuon sach)) trinh nghien tu hoc ) or ( vu bach tranh nghiem d hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( ((co sach) OR (cuon sach)) trinh nghien tu hoc ) or ( vu bach tranh nghiem d hoc ))*.