To me, Atlas Shrugged (1957), and The Fountainhead (1943) are the same book. For the life of me I cannot find a single point in Atlas Shrugged not made in The Fountainhead.
I've read both more than once and, I think, her philosophy, Objectivism, whether you agree or disagree with it, ain't all that complicated. I find the radio address given by John Galt in Atlas Shrugged interminable. She refused to have Atlas Shrugged edited in any way by anyone and it shows.
On the other hand, last I checked, neither book had ever gone out of print, which is impressive, so I could be completely wrong.