Fuentes consultadas1. Advertisement. Whereas proposals have been printed a considerable time since, for publishing, by subscription, a new map of London, Middlesex, Essex, and Hertfordshire; six feet in length, and four in breadth, by actual survey undertaken and performed by John Warburton ... Joseph Bland, and Payler Smyth, this is to acquaint the curious, that the said map is now engraved, and will be published and delivered to subscribers in three months time at farthest, 1725.
2. Tooley, R.V. Tooley's dictionary of mapmakers, 1979 (Smyth, Payler, Surveyor)