Perhaps you should try some spelling variations:
sach doi » sach hoi, sach moi, sach dao
van hanh » van thanh, ban hanh, van anh
sach lo » sach dao, sach hoi, sach moi
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 lo) OR (sach doi)) 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 lo) OR (sach doi)) 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 lo) OR (sach doi)) 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 lo) OR (sach doi)) hang xa hoi. hieu va cac tuc ((va hanh) or (van hanh)) tai cuc tre*.