Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
sach trinh » sach tranh, sach kinh, sach tren
hanh trinh » canh tranh, hanh chinh
trinh viet » ninh viet, trinh vat
nghien tu » nghiep tu, nghien cuu, nghiep vu
toc sach » hoc sach, doc sach, thuoc sach
viet yeu » viet yen, thiet yeu, viet ngu
yeu hoc » yeu hoi, lieu hoc, yeu nuoc
tu hoc » te hoc

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

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