Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
sach ly » sach y, sach lo, sach ty
ly nang » ky nang, ly hang, ly vang
nang o » nang co, nang ho, nang ro
vi cua » vai cua, di cua
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ly nang o hoi. ((((hieu ve) or (hieu van))) or (hieu va)) cau thuc va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ly nang o hoi. ((((hieu ve) OR (hieu van))) OR (hieu va)) cau thuc va hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: thu sach ly nang o hoi. ((((hieu ve) or (hieu van))) or (hieu va)) cau thuc va hanh vi cua tre*.