Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
thanh vi » hanh vi, thanh va, thanh ve
dat ban » bat ban, da ban, day ban
nang ma » tang ma, nang cao, mang may
hac dat » hoc dat, tac dat, hoach dat
van hac » van hoc, van ha, van hai
sang ma » tang ma, sang tao, mang may
sach ky » sac ky, sach ty, sach kem
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuoc ((sach ky) or (sach y)) ((nang ma) or (sang ma)) hoi. hieu van hac dat ban thanh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc ((sach ky) OR (sach y)) ((nang ma) OR (sang ma)) hoi. hieu van hac dat ban thanh vi cua vat.
• Adding a wildcard symbol may retrieve word variants: thuoc ((sach ky) or (sach y)) ((nang ma) or (sang ma)) hoi. hieu van hac dat ban thanh vi cua vat*.