simulation - JK Flip-Flop Counter: How to reset a counter? - Electrical Engineering Stack Exchange
Design steps of 4-bit asynchronous up counter using J-K flip-flop
How to design a synchronous counter 4 bit using JK flip flop that can count up even numbers from 0 to 14, and count down odd numbers from 15 to 0 in 1 system - Quora