Kazimierz Kurz, 21 Jul 2017 Paywalled, but intriguing. You may be able to read one chapter for free (the chapter "Feynman’s Idea... Paywalled, but…
20 Jul 2017 Paywalled, but intriguing. You may be able to read one chapter for free (the chapter "Feynman’s Idea... Paywalled, but…