Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
va trien » va truyen, va thiet, va tuyen
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
toc van » hoc van, toc san, oc van
tac van » tac vang, cac van, tac va
vi va » vi van, vai va, vu va

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 ky nang xa hoi. hieu vien cac ((toc van) OR (tac van)) hanh vi va trien~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. hieu vien cac ((toc van) OR (tac van)) hanh vi va trien".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. hieu vien cac ((toc van) OR (tac van)) hanh vi va trien*.