Recently I have come across one article which I believe you could find interesting. Someone will take a steaming dump all over it, but it answered some of my questions. 
<a href="http://komasiredovisning.se/2018/01/22/principal-unique-groundwork-conventional-paper-on/" / rel="nofollow">http://komasiredovisning.se/2018/01/22/principal-unique-groundwork-conventional-paper-on/</a>