Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
co hoi » co hoc, co loi
ve cac » va cac
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cuu » vi luu, vinh cuu
x hoi » xa hoi, o hoi, x ho

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) or (co hoi)). hieu ((ve cac) or (vien cac)) tu va dan vi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((x hoi) OR (co hoi)). hieu ((ve cac) OR (vien cac)) tu va dan vi cuu tre.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) or (co hoi)). hieu ((ve cac) or (vien cac)) tu va dan vi cuu tre*.