Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
va doanh » van doanh, vay doanh, va danh
cac toi » cac thoi
dan cua » dan ca, ban cua, dai cua
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
cac toc » cac nuoc, cac thoi
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang

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 ty nang xa hoi. hieu van ((cac toc) OR (cac toi)) ((va doanh) or (van dong)) dan cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang xa hoi. hieu van ((cac toc) OR (cac toi)) ((va doanh) OR (van dong)) dan cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang xa hoi. hieu van ((cac toc) OR (cac toi)) ((va doanh) or (van dong)) dan cua tre*".