The CM1 editor does not provide any easy way to add blockquotes with citations. This plugin solves that problem (made for WordPress). If no text is selected when the button is clicked, a pop-up provides fields for “quote”, “citation” and “citation link”. This information is then inserted into the post using proper HTML5 blockquote markup.
Potentially, this could be added as an enhancement to CM1 core. If text is selected, the button maintains the same functionality as the current blockquote button. The pop-up fields only appear when no text is selected.