Perhaps you should try some spelling variations:
hoc thieu » toc thieu, hoc hien
anh quang » anh xquang, anh quan, nhanh quang
tran hong » tran hoang, tran trong, tranh hang
doc hieu » toc thieu, hoc hien
cong bai » cuong bai, cong hai, cung bai
bai toan » bai tap
toan cao » toan ban, toan tap

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: ((doc hieu) OR (hoc thieu)) sach - anh quang ((tran hong) OR (tran quang)) cong bai toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doc hieu) OR (hoc thieu)) sach - anh quang ((tran hong) or (tran quang)) cong bai toan cao~".
• Adding a wildcard symbol may retrieve word variants: ((doc hieu) OR (hoc thieu)) sach - anh quang ((tran hong) or (tran quang)) cong bai toan cao*.