Perhaps you should try some spelling variations:
thanh doi » thanh loi, thanh moi, thanh do
dan thanh » dang thanh, danh thanh, ban thanh
thuc dan » thuc hanh, hoc dan, thuc vat
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
so sach » bo sach, co sach, hoc sach
doi cua » dai cua, hoi cua
van cam » van nam, van lam, van cau
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
so sanh » do sanh
cua tu » cua tuc, cua su, cua cu

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