Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
thuc dan » thuc hanh, hoc dan
tu sach » thu sach, su sach, te sach
cua tre » cua te, cua triet, dua tren
hang di » hang doi, hang vi, hang dien
cuu tre » cau tren, cau treo
sach ky » sac ky, sach y, sach ty
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang

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 lang xa hoi. hieu vien cac ((thuc dan) OR (thuc vat)) hang di ((cua tre) OR (cuu tre))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky lang xa hoi. hieu vien cac ((thuc dan) OR (thuc vat)) hang di ((cua tre) or (cuu tre))~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky lang xa hoi. hieu vien cac ((thuc dan) OR (thuc vat)) hang di ((cua tre) or (cuu tre))*.