Perhaps you should try some spelling variations:
dau khai » dau khi, dan khai, dang khai
te sach » toc sach
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
hieu va » lieu va, hieu qua
dau hai » dai hai, dau ha, cau hai
va coc » va cuoc, va cac, va hoc
luc va » duc va, tuc va, loc va
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 luc va ((dau khai) OR (dau hai)) 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 luc va ((dau khai) OR (dau hai)) cua te~".
• Adding a wildcard symbol may retrieve word variants: te sach ky ((nang xa) or (nang x)) hoi. hieu va coc luc va ((dau khai) OR (dau hai)) cua te*.