Better Blockquotes is a free WordPress plugin created by Devin Price that makes it easy to add citations to blockquotes. When a user clicks the blockquote button with no text highlighted, a dialogue box pops up with options to add a quote, citation, and citation link. Citations are inserted into the post HTML5 markup. The blockquote buttons retains its default behaviour with highlighted text. I tested the plugin on WordPress 4.4 beta 3 and it works as advertised. Price says he’ll attempt to add it to WordPress core as an enhancement.
If you want to see the screenshot of the better blockquote in a post, kindly check at Blockquotes Plugin.