Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
sach trinh » hanh trinh, sach kinh, sach tren
sach tranh » canh tranh
nghiem tin » nghiem tinh, nghiem tien, nghiem tieng
sach trai » sach tai, khach trai, sach tham
nghien d » nghiem d, nghien o, nghiem de
tu sach » thu sach, su sach, te sach
tin hoc » sinh hoc
d hoc » du hoc, ad hoc, de hoc

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

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