The FAS Nuclear Notebook is co-authored by Hans M. Kristensen and Matt Korda and published bi-monthly in the Bulletin of the Atomic Scientists. Each issue provides a snapshot of a nuclear-armed country weapons programs or a global nuclear weapons matter. The FAS Nuclear Notebook is one of the most widely sourced reference materials worldwide for reliable information about the status of nuclear weapons, and it is the most visited section of the Bulletin of the Atomic Scientists web site. Starting in 2020, the Bulletin only offers the Notebooks in web format, but full PDF formats are still available from Taylor & Francis. Because of their importance as a resource to an informed public debate about nuclear weapons, the FAS Nuclear Notebooks are freely available on the Internet.