Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu ve » hieu va, hieu van
vu dang » su dang, vu quang, cua dang
vu lang » va lang, cu lang, tu lang
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau
dan de » dan den, dang de, van de
de cua » le cua, te cua, dieu 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 ((vu lang) OR (vu dang)) xa hoi. hieu ve ((cham soc) or (cham o)) va dan de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((vu lang) OR (vu dang)) xa hoi. hieu ve ((cham soc) OR (cham o)) va dan de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((vu lang) OR (vu dang)) xa hoi. hieu ve ((cham soc) or (cham o)) va dan de cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((vu lang) OR (vu dang)) xa hoi. hieu ve ((cham soc) or (cham o)) va dan de cua tre*.