There are 2 titles associated with this person.

@book{ wphp_12119
  author={Stanhope,Philip Dormer},
  year={1786},
  title={Lord Chesterfield's Maxims; or, A New Plan of Education, on the Principles of Virtue and Politeness. In which is conveyed, such instruction as cannot fail to form the Man of Honour, the Man of Virtue, and the Accomplished Gentleman. Being the substance of the Earl of Chesterfield's Letters, to his Son, Philip Stanhope, Esq; A new edition.},
  publisher={Elizabeth Newbery},
  address={London},    }
@book{ wphp_12120
  author={Stanhope,Philip Dormer},
  year={1793},
  title={Lord Chesterfield's Maxims; or, A New Plan of Education, on the Principles of Virtue and Politeness. In which is conveyed, such instruction as cannot fail to form the Man of Honour, the Man of Virtue, and the Accomplished Gentleman. Being the substance of the Earl of Chesterfield's Letters, to his Son, Philip Stanhope, Esq; A new edition.},
  publisher={Elizabeth Newbery},
  address={London},    }