Perhaps you should try some spelling variations:
khai cua » thai cua, hai cua, khi cua
dau khai » dau khi, dan khai, dau hai
doc thuc » hoc thuc, do thuc, hoc thuoc
te sach » toc sach
sach ky » sac ky, sach y, sach ty
coc tuc » coc luc, hoc thuc, hoc truc
nang xa » lang xa, nang ma, mang xa
hieu va » lieu va, hieu qua
va dau » va dao
cua te » cua tu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky ((nang xa) OR (nang x)) hoi. hieu va ((coc tuc) OR (doc thuc)) va dau khai cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky ((nang xa) or (nang x)) hoi. hieu va ((coc tuc) OR (doc thuc)) va dau khai cua te~".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) or (nang x)) hoi. hieu va ((coc tuc) OR (doc thuc)) va dau khai cua te*.