Perhaps you should try some spelling variations:
dau treo » dau tren, cau treo, dau theo
hieu van » hieu va, thien van, lieu va
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
nam luc » nang luc, nhan luc, nam thuc
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
xay hoi » xa hoi, tay hoi, cay phoi
ly van » le van, ly va, ly von
ky van » ty van, ky va
luc va » duc va, tuc va, loc va
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) OR (su sach)) ((ky van) or (ly van)) xay hoi. hieu van nam luc va hanh va dau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ((ky van) OR (ly van)) xay hoi. hieu van nam luc va hanh va dau treo*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (su sach)) ((ky van) or (ly van)) xay hoi. hieu van nam luc va hanh va dau treo*".