# Derivation of density of states for a gas with $N$ states

I am trying to find any information on the derivation of the density of states for a system with periodic boundary conditions in 3D. I know how it works with 1 particle since I have seen the derivation numerous times, but I can't seem to find any place that explains how it works for a quantum ideal gas of $$N$$ particles. Does anyone have a source?

• You find the answer in standard solid-state physics textbooks, like Ashcroft-Mermin. – flaudemus Feb 18 at 6:10