Perhaps you should try some spelling variations:
thuoc sach » hoc sach, thuat sach, thuoc sinh
nuoc sach » nguoi sach, hoc sach, cuoc cach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va
nang co » nang cao, nang doc, nang noi
co hoi » co hoc, co loi
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: ((thuoc sach) OR (nuoc sach)) ky nang co hoi. ((hieu ve) or (hieu van)) nam thuc va hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thuoc sach) OR (nuoc sach)) ky nang co hoi. ((hieu ve) OR (hieu van)) nam thuc va hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thuoc sach) OR (nuoc sach)) ky nang co hoi. ((hieu ve) or (hieu van)) nam thuc va hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thuoc sach) OR (nuoc sach)) ky nang co hoi. ((hieu ve) or (hieu van)) nam thuc va hanh va cua tre*.