Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
danh vai » danh sai, danh va, doanh van
vai cau » va cau, van cau, vai cac
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
hieu ve » hieu va, hieu van
ve cac » va cac, vien cac
xuc va » tuc va, luc va, xac 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 sang) or (ky tang)) mai hoi. hieu ve cac ((xuc va) OR (duc va)) danh vai 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 cac ((xuc va) OR (duc va)) danh vai 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 cac ((xuc va) OR (duc va)) danh vai cau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky sang) or (ky tang)) mai hoi. hieu ve cac ((xuc va) OR (duc va)) danh vai cau tren*.