Perhaps you should try some spelling variations:
dang thuoc » dung thuoc
nhan dang » phan dang, tran dang
sach hoc » cach hoc, sach hoi, mach hoc
dong hoc » dong co, dong luc
thuoc va » thuc va, thuoc ma, thuong va
nhan dan » phan dau, gian dan, nhan tai
tu sach » thu sach, su sach, te sach
mon hoc » toan hoc
va nhan » van nhan, ca nhan, va phan
va hoi » xa hoi, va hoc, va 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 hoc tap, nghien cuu ((mon hoc) OR (dong hoc)) nhan dang thuoc va hoi va nhan dan~.
• Adding a wildcard symbol may retrieve word variants: tu sach hoc tap, nghien cuu ((mon hoc) or (dong hoc)) nhan dang thuoc va hoi va nhan dan*.