Perhaps you should try some spelling variations:
cau theo » cau thi, cau tao
nang xa » nang x, lang xa, nang ma
qua cac » cua cac
cac toc » cac toi, cac nuoc, cac thoi
cua tre » cua te, cuu tre, cua triet
tu sac » tu sach, tu cac, tu san
sac ky » cac ky, sai ky
toc xa » tuc xa, toc ta, hoc xa
xa don » xa dong, la don, ba don

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky nang xa hoi. hieu qua cac toc xa don vi ((cau theo) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang xa hoi. hieu qua cac toc xa don vi ((cau theo) OR (cua tre)).
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang xa hoi. hieu qua cac toc xa don vi ((cau theo) or (cua tre))*.