Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach vu » sach va, sach tu, sach uu
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
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 ((nang xa) or (lang xa)) hoi. hieu va ((cham soc) or (cham o)) va van de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach vu ((nang xa) OR (lang xa)) hoi. hieu va ((cham soc) OR (cham o)) va van de cua tre.
• Adding a wildcard symbol may retrieve word variants: toc sach vu ((nang xa) or (lang xa)) hoi. hieu va ((cham soc) or (cham o)) va van de cua tre*.