Perhaps you should try some spelling variations:
nhieu vien » nhieu viec, nhiet dien, thieu nien
vien cac » vien bach, vien dai, vien da
trinh he » trinh han, trinh hoa, trinh thi
trinh ve » trinh va, trinh vi, trinh viet
cac duc » cac du, cao duc, cac dac
tu sach » thu sach, te sach, tu cach
nang xa » nang x, lang xa, nang ma
su sach » so sach, vu sach
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ky nang xa hoi. nhieu vien cac duc va ((trinh ve) OR (trinh he)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang xa hoi. nhieu vien cac duc va ((trinh ve) OR (trinh he)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang xa hoi. nhieu vien cac duc va ((trinh ve) OR (trinh he)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang xa hoi. nhieu vien cac duc va ((trinh ve) OR (trinh he)) cua tre*.