Perhaps you should try some spelling variations:
trinh nghien » trinh nghe, kinh nghiem, trinh thiet
hanh trinh » canh tranh, hanh chinh
sach trach » sach truc, sat trach
sach tranh » canh tranh
nghien de » nghiem de, nghiep ke, nghiem d
nhiem van » nghiem van, nhiem va, nghiem ban
lu hanh » luu hanh, du hanh, ly hanh
van hoc » van hoa
de hoc » te hoc, du hoc, dien 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: (( lu hanh trinh nghien de hoc ) OR ( thu ((sach trach) OR (sach tranh)) nhiem van hoc ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( lu hanh trinh nghien de hoc ) or ( thu ((sach trach) OR (sach tranh)) nhiem van hoc ))~".
• Adding a wildcard symbol may retrieve word variants: (( lu hanh trinh nghien de hoc ) or ( thu ((sach trach) OR (sach tranh)) nhiem van hoc ))*.