Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hoc sach » hoc sinh, hoc cac, hoc anh
cau thuc » cau truc, cuu thuc, can thuc
hieu van » hieu va, thien van, lieu va
va danh » va dinh, va hanh, dia danh
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau
vi va » vi van, vai va, vu va

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (hoc sach)) ky nang ma hoi. hieu van cau thuc ((va danh) OR (va dan)) vi va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (hoc sach)) ky nang ma hoi. hieu van cau thuc ((va danh) OR (va dan)) vi va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (hoc sach)) ky nang ma hoi. hieu van cau thuc ((va danh) OR (va dan)) vi va triet".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (hoc sach)) ky nang ma hoi. hieu van cau thuc ((va danh) OR (va dan)) vi va triet*.