Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
su sach » so sach
vu sach » vu bach, vu khach
nang xa » nang x, lang xa, nang ma
toc van » hoc van, tac van, oc van
hanh ve » hanh vi, hanh va, hanh kem
su hien » su kien, su tien, thu hien
y nang » ky nang, ly nang, v nang
ve su » va su

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)) y nang xa hoi. hieu vien bach ((toc van) or (toc san)) hanh ve su hien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) y nang xa hoi. hieu vien bach ((toc van) OR (toc san)) hanh ve su hien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (vu sach)) y nang xa hoi. hieu vien bach ((toc van) or (toc san)) hanh ve su hien".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (vu sach)) y nang xa hoi. hieu vien bach ((toc van) or (toc san)) hanh ve su hien*.