Perhaps you should try some spelling variations:
tai thuoc » tri thuoc, bai thuoc, tac thuoc
hang tai » hang va, dung tai
sach ky » sac ky, sach y, sach ty
co sach » bo sach, cuon sach, hoc sach
hieu ve » hieu va, hieu van
dai hai » dai han, dai hoi, dai tai
mai hoi » mai khoi, dai hoi, lai hoi
ve nhan » ve nha, de nhan, va nhan
luc va » duc va, tuc va
loc va » hoc va
tren » trien, tran, tien

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: co sach ky nang ((mai hoi) or (dai hai)). hieu ve nhan ((luc va) or (loc va)) hang tai thuoc tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co sach ky nang ((mai hoi) OR (dai hai)). hieu ve nhan ((luc va) OR (loc va)) hang tai thuoc tren.
• Adding a wildcard symbol may retrieve word variants: co sach ky nang ((mai hoi) or (dai hai)). hieu ve nhan ((luc va) or (loc va)) hang tai thuoc tren*.