Perhaps you should try some spelling variations:
thanh hoa » thanh pho
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
thuc ban » thuoc ban, thuc dan, thu ban
cam thuc » am thuc, nam thuc, cam thu
hoa cua » hoa chat, hoa xuat
van cam » van nam, van lam, van cau
su sach » so sach, vu sach
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach y, sach 2

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 v ((nang ma) or (sang ma)) hoi. hieu van cam thuc ban thanh hoa cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((nang ma) OR (sang ma)) hoi. hieu van cam thuc ban thanh hoa cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach v ((nang ma) or (sang ma)) hoi. hieu van cam thuc ban thanh hoa cua tre*.