Perhaps you should try some spelling variations:
mach trinh » hanh trinh, sach tranh, mach tich
toan giao » toan cao, hoa giao
trinh do » trinh ky
ton giao » hoc giao, so giao, don gian
vu sach » vu bach, su sach, vu khach
so sach » so sanh, bo sach, co sach
su mach » su sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( ((vu sach) or (so sach)) lich su - toan giao ) or ( su mach trinh do - ton giao ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( ((vu sach) OR (so sach)) lich su - toan giao ) OR ( su mach trinh do - ton giao )).
• Adding a wildcard symbol may retrieve word variants: (( ((vu sach) or (so sach)) lich su - toan giao ) or ( su mach trinh do - ton giao ))*.