Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua
x hoi » xa hoi, o hoi, 5 hoi

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 ky nang ((x hoi) OR (x ho)). ((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 ky nang ((x hoi) OR (x ho)). ((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 ky nang ((x hoi) OR (x ho)). ((hieu ve) or (hieu van)) nam thuc va hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: thuoc sach ky nang ((x hoi) OR (x ho)). ((hieu ve) or (hieu van)) nam thuc va hanh va cua tre*.