I would like Paperpile to support making primary and secondary literature while refering to a source. Today everything is listed in a long common list of citations at the end of the document. It would be nice to be able to mark a citation belonging to secondary literature.
Please 
Thank you for your request, @Odin_Nosen. We are working on a new citation plugin for Google Docs, and the feature to support multiple bibliographies in a single document is part of the feature list. I will check with our product team to find out whether this new feature also includes separate lists for primary and secondary literature at the end of a document.
Here is a possible manual workaround for separate lists of primary and secondary sources: After finishing writing your manuscript, make two copies of it. Remove secondary sources from one copy, remove primary sources from the other copy, and paste each bibliography back into the original document. In the master document, avoid formatting citations after pasting the primary and secondary bibliographies so they aren’t overwritten.