Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
va hanh » va thanh, va danh, ban hanh
cau luc » cau truc, cau phuc
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
sach va » sach xa, sach ha, sach dao
cua tre » cua te, cuu tre, cua triet
sach v » sach y, sach 2, sach vay
va cau » van cau, va cac, va dau
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 v) or (sach va)) lang xa hoi. hieu va cau luc ((va hanh) OR (van hanh)) vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach v) OR (sach va)) lang xa hoi. hieu va cau luc ((va hanh) OR (van hanh)) vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc ((sach v) or (sach va)) lang xa hoi. hieu va cau luc ((va hanh) OR (van hanh)) vi cua tre".
• Adding a wildcard symbol may retrieve word variants: toc ((sach v) or (sach va)) lang xa hoi. hieu va cau luc ((va hanh) OR (van hanh)) vi cua tre*.