Perhaps you should try some spelling variations:
vien cac » vien bach, vien da, gian cac
vien dai » hien dai
van hanh » van thanh, ban hanh, van anh
ve triet » va trien, su triet
so sach » so sanh, bo sach, co sach
tac van » tac vang, cac van, tac va
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho
vi ve » va ve, gi ve, ve ve

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach y nang x hoi. hieu ((vien cac) or (vien dai)) tac van hanh vi ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y nang x hoi. hieu ((vien cac) OR (vien dai)) tac van hanh vi ve triet.
• Adding a wildcard symbol may retrieve word variants: so sach y nang x hoi. hieu ((vien cac) or (vien dai)) tac van hanh vi ve triet*.