Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
hang di » hang doi, hang vi, hang dien
va hang » van hang, va nang, va lang
cac thu » cach thuc, cac thoi
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano
dam tu » nam tu, cam tu, tam tu
di cuu » di cau, di cua, dinh cuu

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 (hoc sach)) tu nang xa hoi. hieu va ((dam tu) or (cac thu)) va hang di cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) tu nang xa hoi. hieu va ((dam tu) OR (cac thu)) va hang di cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (hoc sach)) tu nang xa hoi. hieu va ((dam tu) or (cac thu)) va hang di cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (hoc sach)) tu nang xa hoi. hieu va ((dam tu) or (cac thu)) va hang di cuu tre*.