Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
hieu van » hieu va, thien van, lieu va
dan vinh » dang vinh, danh vinh, van vinh
vinh cua » sinh cua, tinh cua, dinh cua
nang xa » nang x, lang xa, nang ma
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
cam tu » cam thu, nam tu, dam tu
va dan » ca dan, va dao, va dau

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) or (doc sach)) y nang xa hoi. hieu van cam tu va dan vinh cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) y nang xa hoi. hieu van cam tu va dan vinh cua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) y nang xa hoi. hieu van cam tu va dan vinh cua tre*.