Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
canh trinh » canh tranh, hanh trinh, canh tinh
tai nghiem » trai nghiem, thi nghiem, trac nghiem
sach tai » sach bai, sach tham, sach dao
nghiem d » nghiem de, nghiem _, nghiem h
toc canh » luoc canh, ngoc canh, luc canh
nghien h » nghiem h, nghien o, nghiep ha
te sach » toc sach
d hoc » du hoc, ad hoc, de hoc
h hoc » y hoc, _ hoc, o hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( te sach tai nghiem d hoc ) or ( toc canh trinh nghien h hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( te sach tai nghiem d hoc ) OR ( toc canh trinh nghien h hoc )).
• Adding a wildcard symbol may retrieve word variants: (( te sach tai nghiem d hoc ) or ( toc canh trinh nghien h hoc ))*.