The claim that geometric algebra is not rigorous made me confused. But the lack of proper references is much more confusing to me. Back in the days when I was doing research in Chevalley groups the definitive and most cited source was (and still is) Geometric algebra by E. Artin. And there are some more recent treatments recognized in math community, e.g. classical groups and geometric algebra by L. Groove and the geometry of the classical groups by D. Taylor. At least this books made everything rigorous and clear. But may be there is some other field with the same title?
I've heard about book by Doran and always thought that it's more about applications.
The author's argument that Microsoft Word in unavoidable because doc format is de facto standard in his problem domain seems bullshit to me. You can't substitute a document editor with document format like that. I mean, you can totally avoid using Microsoft Word for creating doc files by switching to latex/markdown/org/... with [pandoc][1] converter, for example, or use any kind of MSWord-like word processors, e.g. OpenOffice Writer(if this somehow change something). The author didn't mention any other problem with Word, except it's local ubiquity, which i don't find a problem at all. So, why hate so much?
I've heard about book by Doran and always thought that it's more about applications.