Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
mach tinh » mach tich, manh tinh, trach tinh
trinh son » trinh song, trinh san, tinh son
toan cao » toan ban, toan tap
tu mach » tu cach, tu manh, tu hach
so giao » so giai, hoc giao
du hanh » dieu hanh, duy khanh, luu hanh

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( tu mach tinh toan - so giao ) or ( du hanh trinh son - toan cao ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( tu mach tinh toan - so giao ) OR ( du hanh trinh son - toan cao )).
• Adding a wildcard symbol may retrieve word variants: (( tu mach tinh toan - so giao ) or ( du hanh trinh son - toan cao ))*.