Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
tay lang » tai lang, tay tang, tay quang
thuc dan » thuc hanh, hoc dan, thuc vat
doi cua » hoi cua
so sach » bo sach, co sach, hoc sach
van cam » van nam, van lam, van cau
lang xa » lang ha, dang xay, lang van
so sanh » do sanh

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