Perhaps you should try some spelling variations:
cuon sach » duong sach, cuoc cach, nuoc sach
van hanh » van thanh, ban hanh, van anh
co sach » bo sach, hoc sach
lo hang » ly hang, le hang, cho hang
hang xa » hoang xa, hang va, hang ca
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
va hanh » va thanh, va danh, ban hanh
cuc tre » duc tre, cua tre, cuu tre

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((co sach) OR (cuon sach)) lo hang xa hoi. hieu va cac tuc ((va hanh) or (van hanh)) tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((co sach) OR (cuon sach)) lo hang xa hoi. hieu va cac tuc ((va hanh) OR (van hanh)) tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((co sach) OR (cuon sach)) lo hang xa hoi. hieu va cac tuc ((va hanh) or (van hanh)) tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((co sach) OR (cuon sach)) lo hang xa hoi. hieu va cac tuc ((va hanh) or (van hanh)) tai cuc tre*.