Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
cau treo » cau theo, cau tren, cau triet
vien dai » hien dai
nang xa » nang x, lang xa, nang ma
sach ty » sach y, sach tu, sach thu
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
dai tu » dai thu, tai tu, mai tu

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 (sac ky)) nang xa hoi. hieu vien dai tu va hanh di ((cua tre) or (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sac ky)) nang xa hoi. hieu vien dai tu va hanh di ((cua tre) OR (cau treo)).
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sac ky)) nang xa hoi. hieu vien dai tu va hanh di ((cua tre) or (cau treo))*.