Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
su triet » su viet, su tien, ve triet
danh vai » danh sai, doanh van, dang van
nang mai » nang ma, nang tai, lang mai
sach thu » sach thieu, sach tham, cach thuc
cao duc » dao duc, cao suc, giao duc
danh va » doanh va, hanh va, anh va
hieu va » lieu va, hieu qua
mai hoi » mai khoi, dai hoi, lai hoi
va cao » va cac, va co, 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 thu) or (sach thue)) nang mai hoi. hieu va cao duc va ((danh vai) OR (danh va)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thu) OR (sach thue)) nang mai hoi. hieu va cao duc va ((danh vai) OR (danh va)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thu) or (sach thue)) nang mai hoi. hieu va cao duc va ((danh vai) OR (danh va)) su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach thu) or (sach thue)) nang mai hoi. hieu va cao duc va ((danh vai) OR (danh va)) su triet*.