ELECTROLUNG - Inventor Walter Starck (1972)

                                                  Filming a colony of Garden Eel (1972)


 SKIN DIVER MAGAZINE  300 feet on computerized scuba by Paul Tzimoulis  Sept 1970

https://archive.org/details/sim_skin-diver_1970-09_19_9/mode/2up

Other sites have the Skin Diver pages in PDF 

 

"Before the Electrolung" by Richard Walsby

https://gue.com/blog/the-electrolung-the-first-mixed-gas-rebreather-became-available-for-sport-divers-in-1968/