Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien day » vien dai, vien da, vien xay
day thuc » dan thuc, cay thuc, dai thuc
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
sach ty » sach tu, sach thu, xach tay
xang xa » lang xa, mang xa, ang xa
cua tre » cua te, cuu tre, cua triet
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ty) OR (sach y)) xang xa hoi. hieu vien day thuc van hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) OR (sach y)) xang xa hoi. hieu vien day thuc van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) OR (sach y)) xang xa hoi. hieu vien day thuc van hanh vi cua tre*.