Perhaps you should try some spelling variations:
thuong cong » thong cong, thuong con, thuong dong
chieu sach » chinh sach, chiet tach, chieu xanh
chieu sang » chieu xanh, hieu lang, nhieu tang
trinh quan » tinh quang, trinh luat
cong bai » cuong bai, cong hai, cung bai
bai toan » bai tap
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: ho ((chieu sach) or (chieu sang)) - hanh ((trinh quan) OR (trinh han)) thuong cong bai toan cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ho ((chieu sach) OR (chieu sang)) - hanh ((trinh quan) OR (trinh han)) thuong cong bai toan cao.
• The words AND, OR and NOT may confuse the search; try adding quotes: "ho ((chieu sach) or (chieu sang)) - hanh ((trinh quan) OR (trinh han)) thuong cong bai toan cao".
• Adding a wildcard symbol may retrieve word variants: ho ((chieu sach) or (chieu sang)) - hanh ((trinh quan) OR (trinh han)) thuong cong bai toan cao*.