Perhaps you should try some spelling variations:
mach hinh » manh thinh, sach kinh, mach tich
canh tinh » hanh tinh, manh tinh, canh tranh
tinh son » tinh toan, dinh so, tinh hoc
hoc giao » hoc cao
toan cao » toan ban, toan tap
tu canh » thu canh, tu chanh, tu can
tu mach » tu cach, tu manh, tu hach

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu canh tinh son - hoc giao ) or ( tu mach hinh su - toan cao ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu canh tinh son - hoc giao ) OR ( tu mach hinh su - toan cao ))*.