Article by Barbara Dill explaining multi-axis turning in a logical and thorough manner, with diagrams:
AAW magazine "American Woodturner" December 2011
Sorby eccentric “Wobble” chuck videos:
https://www.robert-sorby.co.uk/lrswc-wobble-chuck
Article and software for Richard Joyner Pendant Jig:
https://nilesbottlestoppers.com/images/pendant-jig-software.pdf
http://huntcountywoodturners.org/index.php/pendant-jig/
JF Escoulen demo:
https://www.youtube.com/watch?v=fecPzCGMnO0
https://www.youtube.com/watch?v=hRT505ucRRA