An Introduction to Magic In Fantasy – http://fantasy-faction.com/2011/magic-in-fantasy

Sanderson’s First Law – http://brandonsanderson.com/sandersons-first-law/

Sanderson’s Second Law – http://brandonsanderson.com/sandersons-second-law/

Sanderson’s Third Law – http://brandonsanderson.com/sandersons-third-law-of-magic/

World Building: Magic Systems – http://www.erindorpress.com/2013/11/world-building-magic-systems/

Magic In Fantasy: Alternative Magic Systems – http://fantasy-faction.com/2014/alternative-magic-systems

12 Questions to Ask Yourself About the System of Magic in Your Fantasy Novel – http://io9.com/5936277/12-questions-to-ask-yourself-about-the-system-of-magic-in-your-fantasy-novel