Context:

Dominic references this book as a source for the episode, stating 'There's a wonderful book about Peter the Great by Robert K. Massey, and I've had to restrain myself from just quoting enormous chunks.' He then quotes from it multiple times, including descriptions of the violence during the Streltsy uprising. The author's name appears as 'Massey' in the transcript but this is likely Robert K. Massie, the Pulitzer Prize-winning historian.