Perhaps you should try some spelling variations:
vien cac » vien dai, vien da, gian cac
van hanh » van thanh, ban hanh, van anh
vu sach » vu bach, su sach, vu khach
sach ky » sac ky, sach y, sach ty
tac van » tac vang, cac van, tac va
su tien » su kien, su hien, tu tieng
x hoi » xa hoi, o hoi, 5 hoi
vi su » va su, ve su, ki su

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