Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
dang xay » dang van, van xay
cua tre » cua te, cuu tre, cua triet
cac tac » cac toc, cac bac, cac dac
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
qua cac » cua cac
tac xa » tuc xa, tac da
xa dan » ca dan, xa dai, va dan
dan vi » doan vi, don vi, dan va

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang xa) or (dang xay)) hoi. hieu qua cac tac xa dan vi ((cua tre) or (su triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang xa) OR (dang xay)) hoi. hieu qua cac tac xa dan vi ((cua tre) OR (su triet)).
• Adding a wildcard symbol may retrieve word variants: su sach ty ((nang xa) or (dang xay)) hoi. hieu qua cac tac xa dan vi ((cua tre) or (su triet))*.