Perhaps you should try some spelling variations:
dieu hien » dieu khien, dieu kien, bieu hien
hieu viec » nhieu viec, hieu ve, sieu viet
doanh co » doanh cua, doanh va, anh co
dang xay » dang van, van xay
danh co » danh cho, anh co, danh ca
cac duc » cac du, cao duc, cac dac
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh
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 ky dang xay hoi. ((dieu hien) or (hieu viec)) cac duc va ((danh co) OR (doanh co)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang xay hoi. ((dieu hien) OR (hieu viec)) cac duc va ((danh co) OR (doanh co)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang xay hoi. ((dieu hien) or (hieu viec)) cac duc va ((danh co) OR (doanh co)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang xay hoi. ((dieu hien) or (hieu viec)) cac duc va ((danh co) OR (doanh co)) cua tre*.