Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
nam thuc » nam thuoc, am thuc, nam thu
dang xay » dang van, van xay
vai cuu » vai cua
cay dan » cac dan, ca dan, cay lanh
day dan » day danh, dao dan, bay dan
qua nam » quan nam, cua nam, quang nam
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, lang van
cuu tre » cua tre, cau tren, cau treo

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: hoc sach ky ((lang xa) OR (dang xay)) hoi. hieu qua nam thuc ((day dan) OR (cay dan)) vai cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach ky ((lang xa) or (dang xay)) hoi. hieu qua nam thuc ((day dan) OR (cay dan)) vai cuu tre~".
• Adding a wildcard symbol may retrieve word variants: hoc sach ky ((lang xa) or (dang xay)) hoi. hieu qua nam thuc ((day dan) OR (cay dan)) vai cuu tre*.