Perhaps you should try some spelling variations:
dao nguoi » cho nguoi
dan nguoi » den nguoi, ban nguoi, dan nuoi
sach hoc » cach hoc, sach hoi, sach duoc
mach hoc » cach hoc, dich hoc, anh hoc
su sach » so sach, vu sach
tu mach » tu cach, tu manh, tu hach
hoc dao » hoc cao, hoc dai, toc dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach hoc dan nguoi ) or ( tu mach hoc dao nguoi ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach hoc dan nguoi ) OR ( tu mach hoc dao nguoi )).
• Adding a wildcard symbol may retrieve word variants: (( su sach hoc dan nguoi ) or ( tu mach hoc dao nguoi ))*.