Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
hanh trinh » canh tranh, hanh chinh
sach trach » sach tranh, sach truc
nghien de » nghiem de, nghiep ke, nghiem d
nhiem dan » nghiem ban, nghiem van, nghiem dau
lu hanh » luu hanh, du hanh, ly hanh
dan hoc » van hoc, dan toc, dai hoc
de hoc » te hoc, du hoc, dien hoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( lu hanh trinh nghien de hoc ) or ( thuoc ((sach trach) OR (sat trach)) nhiem dan hoc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( lu hanh trinh nghien de hoc ) OR ( thuoc ((sach trach) OR (sat trach)) nhiem dan hoc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( lu hanh trinh nghien de hoc ) or ( thuoc ((sach trach) OR (sat trach)) nhiem dan hoc ))".
• Adding a wildcard symbol may retrieve word variants: (( lu hanh trinh nghien de hoc ) or ( thuoc ((sach trach) OR (sat trach)) nhiem dan hoc ))*.