Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
van hanh » van thanh, ban hanh, van anh
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cac toc » cac toi, cac nuoc, cac thoi
vi ve » va ve, gi ve, vi he
ve ve » de ve, va ve, ke ve

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ky nang xa hoi. hieu vien ((cac toc) or (cac hop)) van hanh ((vi ve) OR (ve ve)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky nang xa hoi. hieu vien ((cac toc) OR (cac hop)) van hanh ((vi ve) OR (ve ve)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky nang xa hoi. hieu vien ((cac toc) or (cac hop)) van hanh ((vi ve) OR (ve ve)) triet".
• Adding a wildcard symbol may retrieve word variants: vu sach ky nang xa hoi. hieu vien ((cac toc) or (cac hop)) van hanh ((vi ve) OR (ve ve)) triet*.