Perhaps you should try some spelling variations:
van thanh » van tuan
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
so sach » so sanh, bo sach, co sach
nang xa » nang x, lang xa, nang ma
van cam » van nam, van lam, van cau
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
cua cu » cua chu, cua cau, cua su

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