Perhaps you should try some spelling variations:
danh vai » danh sai, danh va, doanh van
doanh va » doan va, doanh tai, doanh cua
su sach » so sach, vu sach
ky dang » ky nang
ky danh » ky anh
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
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: su sach ((ky dang) OR (ky danh)) xa hoi. hieu va cac duc va ((danh vai) or (doanh va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky dang) OR (ky danh)) xa hoi. hieu va cac duc va ((danh vai) OR (doanh va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky dang) OR (ky danh)) xa hoi. hieu va cac duc va ((danh vai) or (doanh va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky dang) OR (ky danh)) xa hoi. hieu va cac duc va ((danh vai) or (doanh va)) cua tre*.