This might be a ghost discussion. I have worked in scientific publishing for quite some time and have seen citations in the form of: * personal correspondence

This might be a ghost discussion. I have worked in scientific publishing for quite some time and have seen citations in the form of: * personal correspondence * emails * facebook profile pages and my personal highlight * google search queries (I kid you not) All of these citations actually occured in scientific journals. I assume Nicolas Bourbaki was also cited several times, without anyone caring about "academically correct" citation rules. [0]: https://en.wikipedia.org/wiki/Nicolas_Bourbaki https://en.wikipedia.org/wiki/Nicolas_Bourbaki