Perhaps you should try some spelling variations:
cong lang » cong vang, cong luong, cong quang
doc hieu » hoc thieu, hoc hien
phan day » phan dau, phap day, phan xay
dan cong » dang cong, van cong, dan dong
lang van » dang van, tang van, hoang van
day dan » day danh, dao dan, cay dan
van dan » van ban, ban dan, van dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((doc hieu) or (toc thieu)) tinh - phan day dan cong lang van dan ca~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((doc hieu) OR (toc thieu)) tinh - phan day dan cong lang van dan ca.
• Adding a wildcard symbol may retrieve word variants: ((doc hieu) or (toc thieu)) tinh - phan day dan cong lang van dan ca*.