Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
van hoc » van hoa
sach ky » sac ky, sach y, sach ty
van hoe » van hoa, van hieu, van hien
cua tre » cua te, cuu tre, cua triet
sai ky » sac ky
va cua » va chua, via cua, ca cua

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 ky) or (sai ky)) dang ((van hoe) OR (van hoc)). hieu van nam thuc va hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ky) OR (sai ky)) dang ((van hoe) OR (van hoc)). hieu van nam thuc va hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ky) or (sai ky)) dang ((van hoe) OR (van hoc)). hieu van nam thuc va hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: te ((sach ky) or (sai ky)) dang ((van hoe) OR (van hoc)). hieu van nam thuc va hanh va cua tre*.