Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
va hanh » van hanh, va thanh, va danh
cau tac » cau thac, cau tao, cuu tac
so sach » so sanh, bo sach, co sach
tang ma » mang may, tang van
ky tang » ky nang, ky dang, kho tang
van cau » van dau, van hau, van chat
ma hoi » mai hoi, xa hoi, ma hoa
tac va » tac da, tac xa, tuc va
vu van » tu van
vu va » 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) or (hoc sach)) ky tang ma hoi. hieu van cau tac va hanh ((vu va) or (vu van)) trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (hoc sach)) ky tang ma hoi. hieu van cau tac va hanh ((vu va) OR (vu van)) trien.
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (hoc sach)) ky tang ma hoi. hieu van cau tac va hanh ((vu va) or (vu van)) trien*.