Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
day hang » dat hang, dai hang, day nang
thuc day » thuc dan, thuc vat
cam thuc » am thuc, nam thuc, cam thu
ky tang » ky dang, kho tang, ky trong
van cam » van nam, van lam, van cau
so sanh » do sanh
hang di » hang doi, hang vi, hang dien
te sach » toc sach
ha hoi » hoa hoi, ha noi, xa hoi
di cau » da cau, diem cau

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (so sanh)) ((ky tang) or (ky nang)) ha hoi. hieu van cam thuc day hang di cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (so sanh)) ((ky tang) OR (ky nang)) ha hoi. hieu van cam thuc day hang di cau tren.
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (so sanh)) ((ky tang) or (ky nang)) ha hoi. hieu van cam thuc day hang di cau tren*.