Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
te sach » toc sach
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
cau duc » cao duc, cau luc, chu duc
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
vi cua » vai cua, di cua

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

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