Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van hanh » van thanh, ban hanh, van anh
cay thuc » cay thuoc, can thuc, cach thuc
day thuc » dan thuc, dai thuc, dam thuc
su sach » so sach
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
vu sach » vu bach, vu khach
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) OR (vu sach)) ty nang xa hoi. hieu vien ((day thuc) or (cay thuc)) van hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ty nang xa hoi. hieu vien ((day thuc) OR (cay thuc)) van hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (vu sach)) ty nang xa hoi. hieu vien ((day thuc) or (cay thuc)) van hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (vu sach)) ty nang xa hoi. hieu vien ((day thuc) or (cay thuc)) van hanh vi cua tre*.