Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
van hanh » van thanh, ban hanh, van anh
sach ty » sach y, sach tu, sach thu
va hanh » va thanh, va danh, ban hanh
cau luc » cau truc, cau phuc
so sach » so sanh, bo sach, co sach
xang ma » tang ma, nang ma, sang ma
hieu ve » hieu va, hieu van
ma hoi » mai hoi, xa hoi, ma hoa
vu va » vu van, tu va, su va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ty xang ma hoi. ((hieu ve) or (hieu qua)) cau luc ((va hanh) or (van hanh)) vu va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty xang ma hoi. ((hieu ve) OR (hieu qua)) cau luc ((va hanh) OR (van hanh)) vu va triet.
• Adding a wildcard symbol may retrieve word variants: so sach ty xang ma hoi. ((hieu ve) or (hieu qua)) cau luc ((va hanh) or (van hanh)) vu va triet*.