Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
hieu van » thien van, lieu va, hieu ve
hieu va » lieu va, hieu qua
thuc va » thuc dan, thuc day
hanh ca » hanh cac, hanh cat, hanh cua
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
ca cua » co cua
o hai » co hai, so hai, o lai

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 y nang o hai. ((hieu va) or (hieu van)) nam ((thuc va) OR (thuc vat)) hanh ca cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach y nang o hai. ((hieu va) OR (hieu van)) nam ((thuc va) OR (thuc vat)) hanh ca cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach y nang o hai. ((hieu va) or (hieu van)) nam ((thuc va) OR (thuc vat)) hanh ca cua tre*".