Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
va doanh » van doanh, vay doanh, va danh
tu sach » thu sach, su sach, te sach
van cua » vang cua, ban cua, dan cua
ve cham » va cham, ve chat, vu cham
cua tre » cua te, cuu tre, cua triet
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
ve cam » ve cac, va cam, ve cai
luc va » duc va, tuc va, loc va

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 lang) or (ky dang)) xa hoi. hieu ((ve cam) OR (ve cham)) luc va doanh van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky dang)) xa hoi. hieu ((ve cam) OR (ve cham)) luc va doanh van cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) or (ky dang)) xa hoi. hieu ((ve cam) OR (ve cham)) luc va doanh van cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (ky dang)) xa hoi. hieu ((ve cam) OR (ve cham)) luc va doanh van cua tre*.