Perhaps you should try some spelling variations:
toc nguoi » con nguoi
sach hoc » cach hoc, sach hoi, sach duoc
ma nguoi » ca nguoi, va nguoi, cua nguoi
mach hoc » cach hoc, dich hoc, anh hoc
tu sach » thu sach, su sach, te sach
tu mach » tu cach, tu manh, tu hach
hoc toc » hoc hoc, hoc thuoc, hoc toeic

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 ma nguoi ) OR ( tu mach hoc toc nguoi ))~.
• Adding a wildcard symbol may retrieve word variants: (( tu sach hoc ma nguoi ) or ( tu mach hoc toc nguoi ))*.