Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
cac tac » cac toc, cac bac, cac dac
van mat » van dat, van man, van mao
mat cau » mau cau, dat cau, mat can
y nang » ky nang, ly nang, v nang
tac va » tac da, tac xa, tuc va

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y nang xa hoi. ((hieu va) or (lieu va)) cac tac va van mat cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang xa hoi. ((hieu va) OR (lieu va)) cac tac va van mat cau tren*.