It would be almost impossible to write down “all” of the equations used in electronics. But, they all can be derived from a few basic principals (or equations). You should become so familiar with these first principals that the few equations that express them are just part of your work a day vocabulary. Things like Ohm's law and resonant frequency equations, should be second nature and generally, things that are more complex either are more complex because you have made it more complex because you don’t understand the fundamental principals that are involved, or you are dealing with something that is so specialized that you simply will have to go back to the books.
But, nonetheless, I keep basic circuits and equations that I rarely need, on 5X7 cards in a file. The card is big enough that I can have examples of how to use the equation. I also keep circuit ideas in my 5X7 card file.