Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hanh dao » lanh dao, thanh dat, thanh dam
tan hanh » tan thanh, tang hanh, toan hanh
sach thu » sach thue, sach thieu, sach tham
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, xach tay
sang ma » tang ma, nang ma, sang tao
hieu ve » hieu van
ma hoi » mai hoi, xa hoi, ma hoa
dao va » dao van, tao va, do va

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 ty) or (sach thu)) sang ma hoi. ((hieu ve) OR (hieu va)) pham duc tan hanh dao va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach thu)) sang ma hoi. ((hieu ve) OR (hieu va)) pham duc tan hanh dao va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) or (sach thu)) sang ma hoi. ((hieu ve) OR (hieu va)) pham duc tan hanh dao va triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sach thu)) sang ma hoi. ((hieu ve) OR (hieu va)) pham duc tan hanh dao va triet*.