Further information on the development of the calculus can be found in several good books. Margaret Baron's The Origins of the Infinitesimal Calculus [2] deals with many of the methods of the calculus up to the time of Newton and Leibniz. C. H. Edwards' The Historical Development of the Calculus [7] also shows how mathematicians calculated solutions to problems, but covers in more detail the work of Newton, Leibniz, and their successors. The classic work by Carl Boyer, The History of the Calculus and its Conceptual Development [4];, concentrates more on the central ideas of the calculus rather than the technical details.

The mathematical work of Newton is available in English translation in the magnificent set, The Mathematical Papers of Isaac Newton [14], edited by D. T. Whiteside. In addition, there is a new English translation and commentary on Newton's Principia [10], by I. Bernard Cohen and Anne Whitman. Among the many other books which help the reader understand Newton's masterwork are Niccoló Guicciardini's Reading the Principia [9] and Dana Densmore's Newton's Principia: The Central Argument [6]. Both of these books deal further with the question that Pourciau considers, along with much other material. Leibniz's works are unfortunately not all available in English, but some of his early manuscripts have been collected and translated by J. M. Child in The Early Mathematical Manuscripts of Leibniz [5]. For an introduction to either man's work, it might be best to look through one of the standard biographies: Never at Rest [13] by Richard Westfall for Newton, and Leibniz: A Biography [1] by Eric Aiton for Leibniz.