NASA
Nasa: Astronomy Picture of the Day: Crab Nebula and Geminga in Gamma Rays
Explains that pulsars would be the brightest objects in the sky if we could see gamma-rays.
NASA
Nasa: Imagine the Universe: Gamma Ray Bursts
What is a Gamma-ray Burst? Why do scientists study gamma-ray bursts? Find your answers to these questions as well as view additional resources on this topic.