Perhaps you should try some spelling variations:
hanh trinh » canh tranh, hanh chinh
hieu quan » hieu qua, lieu quan, thien quan
trinh qua » trinh quan, trinh cua, trinh quang
hoi hieu » hoi phieu, hoi tieu, moi hieu
hong tac » huong tac, cong tac, dong tac
tac toan » tap toan, tam toan, hach toan
toan cao » toan ban, toan tap

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoi hieu quan - hanh trinh qua (song OR dong) hong tac toan cao~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoi hieu quan - hanh trinh qua (song OR dong) hong tac toan cao".
• Adding a wildcard symbol may retrieve word variants: hoi hieu quan - hanh trinh qua (song OR dong) hong tac toan cao*.