Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
thu sach » tu sach, thuat sach, thuoc sach
thu hang » thi hang, thuc hanh, thu huong
va doanh » van doanh, vay doanh, va danh
van chu » van chi, van phu, van cau
chu tre » cho tre, chu tri, cuu tre
hieu va » lieu va
ca cao » ca dao, cu cao, ca cac
cao va » cao van, tao va, co va
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: ((thu sach) or (thu hang)) ky nang x hoi. ((hieu va) OR (hieu qua)) ca cao va doanh van chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (thu hang)) ky nang x hoi. ((hieu va) OR (hieu qua)) ca cao va doanh van chu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (thu hang)) ky nang x hoi. ((hieu va) OR (hieu qua)) ca cao va doanh van chu tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (thu hang)) ky nang x hoi. ((hieu va) OR (hieu qua)) ca cao va doanh van chu tre*.