Abstract
A philosopher may develop ideas on his or her own or follow them in the works of others. Different kinds of documentary threads will develop. Historians of a subject may follow either kind. In the period of _Toward “Principia Mathematica”, 1905–08_, Russell engaged with developments in the writings of Poincaré, Haldane, Schiller and Berry, among others. What follows are remarks on supplementary documents (one being on-line) for a fuller study of logical and philosophical threads in the period.