Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach vu » sach va, sach tu, sach uu
dan den » ban den, van den, dan dung
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
vu nang » vuc nang, va nang, vu dang
dan de » dang de, van de, dan da

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 vu nang xa hoi. hieu ve ((cham soc) or (cham o)) ca ((dan de) OR (dan den)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach vu nang xa hoi. hieu ve ((cham soc) OR (cham o)) ca ((dan de) OR (dan den)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach vu nang xa hoi. hieu ve ((cham soc) or (cham o)) ca ((dan de) OR (dan den)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach vu nang xa hoi. hieu ve ((cham soc) or (cham o)) ca ((dan de) OR (dan den)) cua tre*.