The immediate source of the play has not been identified, but in the Introduction attention has been drawn to passages in the writings of Bussy's contemporaries, especially BrantÔme and Marguerite de Valois, which narrate episodes similar to those in the earlier Acts. Extracts from De Thou's Historiae sui temporis and Rosset's Histoires Tragiques, which tell the tale of Bussy's amorous intrigue and his assassination, have also been reprinted as an Appendix. But both these narratives are later than the play. Seneca's representation in the Hercules Œtaeus of the Greek hero's destruction by treachery gave Chapman suggestions for his treatment of the final episode in Bussy's career (cf. v, 4, 100-108, and note).