Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
mai khoi » mai khoa, tai khoa, cac khoi
danh sai » dung sai, danh bat, danh dau
cau tren » cu tren, dau tren, ca tren
mai hoi » dai hoi, lai hoi, mai doi
sach ky » sac ky, sach y, sach ty
ky sang » ky nang, ky dang, ky tang
sai cau » lai chau, mai chau, hai chau
hieu ve » hieu va, hieu van
ve cam » ve cham, ve cac, va cam
xac va » tac va, ac va, bac 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 khoi)). hieu ve cam ((xac va) or (duc va)) 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 khoi)). hieu ve cam ((xac va) OR (duc va)) danh sai cau tren.
• Adding a wildcard symbol may retrieve word variants: thu sach ky sang ((mai hoi) or (mai khoi)). hieu ve cam ((xac va) or (duc va)) danh sai cau tren*.