Cliff Reiter wrote one of the best ever J books as well.<p><a href="https://www.amazon.com/Fractals-Visualization-Fourth-Clifford-Reiter/dp/1329873556" rel="nofollow">https://www.amazon.com/Fractals-Visualization-Fourth-Cliffor...</a><p>You can run some of the examples by downloading J, installing the labs in the package manager and selecting help->studio->labs->Fractals