these citations are for use in derivations

@book{2001_HRW,
title = {Fundamental Physics},
author = {Halliday, Resnick, Walker},
edition = {6th},
year = {2001}
}

@book{1999_Tipler_Llewellyn,
title = {Modern Physics},
author = {Tipler and Llewellyn}
edition = {Third},
year = {1999}
}