Perhaps you should try some spelling variations:
cham hoc » cham soc, chat hoc, cham hoi
danh vai » danh sai, doanh van, dang van
tu sach » thu sach, su sach, te sach
va cham » va chat, va tham
danh va » doanh va, hanh va, anh va
cua tre » cua te, cuu tre, cua triet
y tang » ky tang, 7 tang, 5 tang
ma hoi » mai hoi, xa hoi, ma hoa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y tang) OR (6 tang)) ma hoi. lieu va cham hoc va ((danh vai) OR (danh va)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y tang) or (6 tang)) ma hoi. lieu va cham hoc va ((danh vai) OR (danh va)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y tang) or (6 tang)) ma hoi. lieu va cham hoc va ((danh vai) OR (danh va)) cua tre*.