Perhaps you should try some spelling variations:
nang cau » nang cao, hang cau, nang dau
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
cua cau » cua cac, cua chu, cua cay
va dan » ca dan, va dao, va dau
ca cau » cac cau, can cau, ca cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang cau hoi. hieu van nam thuc va dan ((ca cau) or (cua cau)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang cau hoi. hieu van nam thuc va dan ((ca cau) OR (cua cau)) tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang cau hoi. hieu van nam thuc va dan ((ca cau) or (cua cau)) tren*.