See article (http://meta.ath0.com/2012/02/05/apples-great-gpl-purge/)from previous HN post: https://news.ycombinator.com/item?id=3559990
Also, GNU's bulletin on Apple Boycott: https://www.gnu.org/bulletins/bull18.html#SEC13
And also this article which explains why apple is BSD mostly: https://scalibq.wordpress.com/2012/08/02/apples-os-x-is-not-...