Perhaps you should try some spelling variations:
vien cac » vien dai, vien da, gian cac
van hanh » van thanh, ban hanh, van anh
va trien » va truyen, va thiet, va tuyen
su sach » vu sach
so sach » so sanh, bo sach, co sach
nang xa » nang x, lang xa, nang ma
toc van » hoc van, toc san, tac van
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) or (so sach)) ky nang xa hoi. hieu ((vien cac) OR (vien bach)) toc van hanh vi va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ky nang xa hoi. hieu ((vien cac) OR (vien bach)) toc van hanh vi va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) ky nang xa hoi. hieu ((vien cac) OR (vien bach)) toc van hanh vi va trien".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) ky nang xa hoi. hieu ((vien cac) OR (vien bach)) toc van hanh vi va trien*.