The ISEN is a good place to start. There are book recommendations as well as videos to watch.
My favourite book is this one: The Electroconvulsive Therapy Workbook: Clinical Applications . It is Australian but the content is not Aus specific. It is comprehensive and suitable for both medical and nursing staff. It includes both the MECTA and Thymatron devices ( I'm assuming by 4-knob you are referring to a MECTA device).