Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
dieu cua » dieu tra
anh dieu » hanh dieu, anh sieu, nganh dieu
van anh » van thanh, tuan anh, van minh
cua tre » cua te, cuu tre, cua triet
ky tang » ky nang, ky dang, kho tang
tang ma » mang may, tang van
tu sach » thu sach, su sach, te sach
cac co » cac cong
cac lo » cac lop, cac bo, cac ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu hoach) or (tu sach)) ky tang ma hoa. hieu vien ((cac lo) OR (cac co)) van anh dieu cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu hoach) OR (tu sach)) ky tang ma hoa. hieu vien ((cac lo) OR (cac co)) van anh dieu cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu hoach) or (tu sach)) ky tang ma hoa. hieu vien ((cac lo) OR (cac co)) van anh dieu cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu hoach) or (tu sach)) ky tang ma hoa. hieu vien ((cac lo) OR (cac co)) van anh dieu cua tre*.