Perhaps you should try some spelling variations:
doi chieu » doc hieu, doi chi, mot chieu
hanh hang » thanh hang, hanh han, hanh mang
hang hang » nang hang, cang thang, hung thang
dung khoa » dung cho
ho chieu » theo chieu, hoc thieu, mot chieu
khoa can » khoa cam, khoa cap, khoi can
tan toan » tan tran, tap toan, van toan
toan cao » toan ban, toan tap
can tan » can ban, van tan, can van

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((ho chieu) OR (doi chieu)) xanh - ((hanh hang) or (hang hang)) dung khoa can tan toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((ho chieu) OR (doi chieu)) xanh - ((hanh hang) OR (hang hang)) dung khoa can tan toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((ho chieu) OR (doi chieu)) xanh - ((hanh hang) or (hang hang)) dung khoa can tan toan cao".
• Adding a wildcard symbol may retrieve word variants: ((ho chieu) OR (doi chieu)) xanh - ((hanh hang) or (hang hang)) dung khoa can tan toan cao*.