There are 5 titles associated with this firm.

@book{ wphp_11004
  author={Hemans,Felicia},
  year={1833},
  title={Hymns on the Works of Nature. For the Use of Children. By Mrs. Felicia Hemans.},
  publisher={John Mardon [St. Martin's-Le-Grand] \& },
  address={London},    }
@book{ wphp_10222
  author={Follen,Eliza Lee Cabot},
  year={1833},
  title={Sequel to "The well-spent hour", or, The birth-day. By the author of the "Well-spent hour," &c, &c.},
  publisher={John Mardon [St. Martin's-Le-Grand] \& },
  address={London},    }
@book{ wphp_1525
  author={Savage,Sarah},
  year={1835},
  title={Trial and Self-Discipline. By Miss Savage, Author of ‘James Talbot,’ ‘The Factory Girl,’ &C.},
  publisher={Simpkin, Marshall and Co. \& },
  address={London},    }
@book{ wphp_1523
  author={Follen,Eliza Lee Cabot},
  year={1835},
  title={The Sceptic. By Mrs. Follen, Author of ‘The Well-Spent Hour,’ &C.},
  publisher={Simpkin, Marshall and Co. \& John Mardon [St. Martin's-Le-Grand]},
  address={London},    }
@book{ wphp_1527
  author={Sedgwick,Catharine Maria},
  year={1836},
  title={Home. By Miss Sedgwick, Author of “Redwood,” “Hope Leslie,” &c.},
  publisher={Simpkin, Marshall and Co. \& },
  address={London},    }