There are two editions of Quinn's book, and they are significantly different: to dig really deeply into Joseph Smith's occultism, you'll need to consult both editions. The first edition (1987) included massive documentation of every claim Quinn made, citing many very obscure sources in lengthy footnotes. The second edition (1998) had more of Quinn's own further research, but to make room for that added material, much of the documentation had to be cut back. I would recommend starting with the second edition, and then consulting the first edition's footnotes as well on any point that seems particularly relevant to your own thoughts.

One can find both editions of Quinn here and there online, and also Brooke's volume. Brook is less interested in outright magical practices than Quinn, but more interested in American hermetic philosophy and alchemy of Smith's era and earlier. (Early America was very far from being a strictly Protestant Christian land. There was an enormous amount of occultism and mysticism going around, especially in the rural parts of the country, away from the surveillance of the higher-ups. Academic scholarship is just beginning top scratch the surface of what was there.)

In short, Quinn and Brooke complement one another nicely.