Perhaps you should try some spelling variations:
hanh trinh » hanh chinh
trong mach » trong cac, trong minh, trong anh
hieu quan » hieu qua, lieu quan, thien quan
mach toan » manh toan, hach toan, mach tuan
cua dung » cua dong, qua dung, cua rung
cua dang » cua cong, cua ban
toan cao » toan ban, toan tap
ho hieu » ho chieu, hoi hieu, nho hieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ho hieu quan - ((hanh trinh) or (canh tranh)) ((cua dung) OR (cua dang)) trong mach toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho hieu quan - ((hanh trinh) OR (canh tranh)) ((cua dung) OR (cua dang)) trong mach toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho hieu quan - ((hanh trinh) or (canh tranh)) ((cua dung) OR (cua dang)) trong mach toan cao".
• Adding a wildcard symbol may retrieve word variants: ho hieu quan - ((hanh trinh) or (canh tranh)) ((cua dung) OR (cua dang)) trong mach toan cao*.