Perhaps you should try some spelling variations:
hieu vien » hieu hien, hieu viec, thieu nien
vien cac » vien bach, vien dai, vien da
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cac toi » cac thoi
toi van » thi van, tri van, doi van
x hoi » xa hoi, o hoi, x ho
vi ve » gi ve, vi he
va ve » va de, va le, va vi
ve ve » de ve, ke ve, ve ke

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