David Hestenes, Adv. Appl. Clifford Algebras, Vol. 24 (2014), pp. 257-273, http://link.springer.com/article/10.1007%2Fs00006-013-0418-0, DOI: 10.1007/s00006-013-0418-0
Abstract: The book Clifford Algebra to Geometric Calculus is the first and still the most complete exposition of Geometric Calculus (GC). But it is more of a reference book than a textbook, so can it be a difficult read for beginners. This tutorial is a guide for serious students who want to dig deeply into the subject. It presents helpful background and aims to clarify objectives, important results and methods in the book. It is supplemented by a hot-linked annotated bibliography of papers elaborating various aspects of Geometric Algebra and Calculus.
PDF file on author page with PDF hot-links to papers in bibliography: http://geocalc.clas.asu.edu/pdf/Tutorial%20on%20Geometric%20Calculus.pdf
Source: D. Hestenes (ICCA10 conference, Tartu), http://link.springer.com/article/10.1007%2Fs00006-013-0418-0, http://geocalc.clas.asu.edu/pdf/Tutorial%20on%20Geometric%20Calculus.pdf