Perhaps you should try some spelling variations:
trong thai » trong thi, trong thoi, trong thuat
trong hai » trong tai, trong hoat, trong phat
bang cong » dang cong, bang song, hang cong
ho chieu » theo chieu, hoc thieu, doi chieu
cong tap » cuong tap, cong tac, cong tan
tap toan » tap doan, tap quan, bai toan
toan cau » toan cao, toan ban, toan tap
doi chi » doi khi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doi chi) or (ho chieu)) sach - thanh ((trong hai) OR (trong thai)) bang cong tap toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doi chi) OR (ho chieu)) sach - thanh ((trong hai) OR (trong thai)) bang cong tap toan cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((doi chi) or (ho chieu)) sach - thanh ((trong hai) OR (trong thai)) bang cong tap toan cau".
• Adding a wildcard symbol may retrieve word variants: ((doi chi) or (ho chieu)) sach - thanh ((trong hai) OR (trong thai)) bang cong tap toan cau*.