Perhaps you should try some spelling variations:
doanh van » doan van, doanh va, doanh ban
cau tren » cu tren, dau tren, ca tren
danh vai » danh sai, danh va, dang van
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
xuc va » duc va, tuc va, luc va
ve cam » ve cham, ve cac, va cam

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 sang) or (ky tang)) mai hoi. hieu ve cam xuc va ((danh vai) OR (doanh van)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky sang) OR (ky tang)) mai hoi. hieu ve cam xuc va ((danh vai) OR (doanh van)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky sang) or (ky tang)) mai hoi. hieu ve cam xuc va ((danh vai) OR (doanh van)) cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky sang) or (ky tang)) mai hoi. hieu ve cam xuc va ((danh vai) OR (doanh van)) cau tren*.