https://www.inner-magazines.com/audiophilia/philips-rh-545-studio
https://stereonomono.blogspot.com/2015/03/philips-545-mfb-studio.html
https://www.mfbfreaks.nl/motional-feedback-mfb/
https://www.mfbfreaks.nl/philips-productontwikkeling-1975/