Perhaps you should try some spelling variations:
"su mach hoc lam nguoi" » "su mach hoc tay nguoi", "su cach hoc lam nguoi", "su dich hoc lam nguoi", "su anh hoc lam nguoi", "su mach duoc lam nguoi"
"su sach hoc dao nguoi" » "su sach hoc cho nguoi", "su cach hoc dao nguoi", "su sach hoi dao nguoi", "su sach duoc dao nguoi", "so sach hoc dao nguoi", "vu sach hoc dao nguoi", "su sach hoc dan nguoi", "su sach hoc cao nguoi", "su sach hoc dai nguoi"
"su sach hoc co nguoi" » "su cach hoc co nguoi", "su sach hoi co nguoi", "su sach duoc co nguoi", "su sach hoc cho nguoi", "su sach hoc con nguoi", "su sach hoc o nguoi", "so sach hoc co nguoi", "vu sach hoc co nguoi", "su sach hoc cao nguoi"

Try widening your search to All Fields.

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

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