It is showing up on web trees that Mary Stuart married, as her second husband, Philip de Carteret. 1st Baronet Philippe De Carteret, III
This surprised me, as it doesn’t show up in the histories that I know.
Are there primary or reliable secondary sources?
Quick and dirty, Wikipedia for Mary: https://en.wikipedia.org/wiki/Mary,_Princess_Royal_and_Princess_of_...
For Philip: https://en.wikipedia.org/wiki/Sir_Philip_Carteret,_1st_Baronet
No mention in either of the other.