Perhaps you should try some spelling variations:
nhung cong » dung cong, thong cong, hang cong
trinh cua » trinh luat, trinh quan, trinh luan
toc hieu » toc thieu, doc hieu, hoc thieu
hieu cac » hieu luc, hieu va, hieu van
tinh cua » sinh cua, tinh chat, tranh cua
san toan » van toan, manh toan, xuan toan
dan toan » van toan, dan than, manh toan

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

• If you are trying to use Boolean operators, they must be ALL CAPS: toc hieu cac - hanh ((trinh cua) OR (tinh cua)) nhung cong ((san toan) OR (dan toan)) ban~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc hieu cac - hanh ((trinh cua) OR (tinh cua)) nhung cong ((san toan) or (dan toan)) ban~".
• Adding a wildcard symbol may retrieve word variants: toc hieu cac - hanh ((trinh cua) OR (tinh cua)) nhung cong ((san toan) or (dan toan)) ban*.