Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
thanh di » thanh doi, thanh de, thanh do
cua viet » ca viet, hoa viet, cua dieu
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
cau tuc » cau truc, cau tu, cau luc
tuc ban » thuc ban, truc ban, tu ban
ma hoi » mai hoi, xa hoi, ma hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (thu hoach)) ky nang ma hoi. hieu van cau tuc ban thanh di ((cua viet) OR (cua vat))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (thu hoach)) ky nang ma hoi. hieu van cau tuc ban thanh di ((cua viet) OR (cua vat))~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (thu hoach)) ky nang ma hoi. hieu van cau tuc ban thanh di ((cua viet) OR (cua vat))*.