Perhaps you should try some spelling variations:
trach nhiem » trac nghiem
hanh trinh » hanh chinh
sach trach » sach tranh, sach truc, sat trach
nghien de » nghiem de, nghiep ke, nghiem d
nhiem dan » nghiem ban, nghiem van, nghiem dau
tu sach » thu sach, su sach, te sach
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) OR (canh tranh)) nghien de hoc ) or ( tu sach trach nhiem dan toc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( lu ((hanh trinh) OR (canh tranh)) nghien de hoc ) OR ( tu sach trach nhiem dan toc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( lu ((hanh trinh) OR (canh tranh)) nghien de hoc ) or ( tu sach trach nhiem dan toc ))".
• Adding a wildcard symbol may retrieve word variants: (( lu ((hanh trinh) OR (canh tranh)) nghien de hoc ) or ( tu sach trach nhiem dan toc ))*.