Perhaps you should try some spelling variations:
trinh chuan » trinh quan, trinh luan, trinh phan
cong thang » cong thanh, cang thang, cong thong
trinh han » trinh quan
bang cong » dang cong, bang song, hang cong
cong cong » cong dong, trong cong, dung cong
chi hanh » chi nhanh, chi thanh, thi hanh
thang va » hang va, trang va, thong va
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 hanh - canh ((trinh chuan) or (trinh han)) bang cong cong thang va~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doi chi hanh - canh ((trinh chuan) OR (trinh han)) bang cong cong thang va*.