Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
mai khoa » tai khoa, may khoa, dai khoa
danh sai » dung sai, danh bat, danh dau
danh vai » danh va, doanh van, dang van
cau tren » cu tren, dau tren, ca tren
mai hoi » mai khoi, dai hoi, lai hoi
sach ky » sac ky, sach y, sach ty
ve cham » va cham, ve chat, vu cham
ky sang » ky nang, ky dang, ky tang
hieu ve » hieu va, hieu van
soc va » hoc va, loc va, doc va

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