Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
nghiem dan » nghiem ban, nghiem dau, nghiep dan
nghiem van » nghiem va, nghiem ban, nghiep van
canh trinh » canh tranh, hanh trinh, canh tinh
nghien ban » nghiem ban, nghiep ban, nghiep bang
sach trai » sach tai, sach tranh, khach trai
toc sach » hoc sach, doc sach, thuoc sach
tu canh » thu canh, tu chanh, tu can
ban hoc » bang hoc, van hoc, bai 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 trai ((nghiem dan) OR (nghiem van)) toc ) or ( tu canh trinh nghien ban hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( toc sach trai ((nghiem dan) OR (nghiem van)) toc ) OR ( tu canh trinh nghien ban hoc ))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( toc sach trai ((nghiem dan) OR (nghiem van)) toc ) or ( tu canh trinh nghien ban hoc ))*".