Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
hieu va » lieu va, hieu qua
va hoc » van hoc
va dau » va dao
de cua » le cua, dieu cua
te cua » tue cua, le cua
nuoc » quoc, duoc, ngoc

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: tu sach ky ((nang xa) OR (nang x)) hoi. hieu va hoc nuoc va dau ((de cua) OR (te cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (nang x)) hoi. hieu va hoc nuoc va dau ((de cua) OR (te cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang x)) hoi. hieu va hoc nuoc va dau ((de cua) OR (te cua)) tre*.