Ive got that book and its great and nice and cheap compared to other scorp books.
One book I wouldnt really recommend is "Scorpions: Plus other popular Invertebrates" by Jerry G. Walls and published Advanced Vivarium Systems.
Its and ok book but its doesnt cover scorps in any great detail, the scorp section only goes as far as page 59 and the rest of the book (as far as page 82 then the rest is the Index) talks breifly about Amblypygids, Uropygids, Millipedes, Centipedes, Mantids, Phasmids and Solpugids. I would only recommend this book for someone who cant find the Manny Rubio book and wants a quick scorp related read on the bog

(its no that bad it's just what I use it for

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2x Pandinus Imperator - 17x Heterometrus Petersii - 1x Hadogenes Paucidens - 1x Hoffmanius Spinigerus - 1x Hadrurus Arizonensis
1x Archispirostreptus Gigas