Gigaleak: Game Boy Advance BIOS and Game Boy Color Boot ROM development repositories, Link's Awakening DX source code and much more : r/Gameboy
GBA Bios - Gameboy Advance BIOS - Download
Developer Jeff on Twitter: "Prototype Gameboy Advanced Development Kit "IS CGB/AGB Emulator Box Ver.01" With a prototype Nintendo Gameboy Advanced system in unreleased Lemon Yellow! More pictures and teardown to come! Any
Bios GBA Portrait by LeandroValhalla on DeviantArt