https://dl.acm.org/doi/10.1145/3386332 https://dl.acm.org/doi/10.1145/3386332 - The Origins of Objective-C at PPI/Stepstone and its Evolution at NeXT by Brad J.

https://dl.acm.org/doi/10.1145/3386332 https://dl.acm.org/doi/10.1145/3386332 - The Origins of Objective-C at PPI/Stepstone and its Evolution at NeXT by Brad J. Cox, Steve Naroff, and Hansen Hsu, from HOPL IV