Niccoló Solo is used as a narrator on the Infernal Dwarves. In T9A:FB Rulebook he is presented as a famed merchant traveller together with an extract from his book the Book of Terrors of the World. The extract describes the Solo's encounter with the Steel Road. It is a first hand source but is only confirmed by the source itself.
Solo also appears as a narrator in The 9th Scroll issue #7, where he is presented as the writer as a note detailing the citadels of the Infernal Dwarves.