Self-published sources are generally not considered reliable: i.e. anyone can't just write a web page or a book and start quoting themselves on Wikipedia. That's clearly objectionable!
Recognized domain experts who are routinely published in respectable journals is one of the main exceptions.
Recognized domain experts who are routinely published in respectable journals is one of the main exceptions.
Some relevant policy: https://en.m.wikipedia.org/wiki/Wikipedia:Verifiability#Self...