Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va thanh » gia thanh, ban thanh, va tinh
va hanh » van hanh, va danh, ban hanh
cac cao » cac co, ca cao, bac cao
hieu ve » hieu va, hieu van
cao hoi » cau hoi, co hoi, cao hoc
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
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: ((toc sach) or (dac sac)) ky nang cao hoi. hieu ve cac cao ((va hanh) or (va thanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (dac sac)) ky nang cao hoi. hieu ve cac cao ((va hanh) OR (va thanh)) vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (dac sac)) ky nang cao hoi. hieu ve cac cao ((va hanh) or (va thanh)) vi cua tre*.