Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cam thuc » am thuc, nam thuc, cam thu
va thanh » gia thanh, va tinh, le thanh
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
van cam » van nam, van lam, van cau
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach y, sach 2
ha cua » hoa cua, hai cua, nha cua

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 xa) or (lang xa)) hoi. hieu van cam thuc ((va thanh) OR (ban thanh)) ha cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v ((nang xa) OR (lang xa)) hoi. hieu van cam thuc ((va thanh) OR (ban thanh)) ha cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v ((nang xa) or (lang xa)) hoi. hieu van cam thuc ((va thanh) OR (ban thanh)) ha cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach v ((nang xa) or (lang xa)) hoi. hieu van cam thuc ((va thanh) OR (ban thanh)) ha cua tre*.