The most reliable source is the SparkFun-Eagle-Libraries GitHub repository .
To use the Pro Micro footprint in your design, you must first import the .lbr file into . Arduino Forumhttps://forum.arduino.cc Eagle Library for Arduino Pro Micro - General Electronics arduino+pro+micro+eagle+library
The "Pro Micro" was originally developed by , and its official Eagle files are widely considered the industry standard. arduino+pro+micro+eagle+library