There are 3 titles associated with this firm.

@book{ wphp_6076
  author={Fowke,Martha},
  year={1752},
  title={Clio: or, a secret history of the life and amours of the late celebrated Mrs. S---n---m. Written by herself, in a letter to Hillarius.},
  publisher={Robert Main},
  address={Dublin},    }
@book{ wphp_6353
  author={Blandy,Mary},
  year={1752},
  title={Miss Mary Blandy's own account of the affair between her and Mr. Cranstoun, from the commencement of their acquaintance, in the year 1746, to the death of her father, in August, 1751. With all the circumstances leading to that unhappy event. To which is added, an appendix, containing copies of some original letters now in possession of the editor. Together with an exact relation of her behaviour, while under sentence; and a copy of the declaration signed by herself, in the presence of two clergymen, two days before her execution. Published at her dying request.},
  publisher={Andrew Millar \& Robert Main \& Oliver Nelson \& John Exshaw I [Cork Hill]},
  address={Dublin},    }
@book{ wphp_10517
  author={Mayne,Frances},
  year={1767},
  title={An introduction to the reading of the Holy Bible.},
  publisher={Robert Main},
  address={London},    }