https://books.google.com/books?id=e649C ... 47&f=false
Cengarle, Federica, Covini, Maria Nadia (eds.), Ducato di Filippo Maria Visconti, 1412-1447. Economia, politica, cultura, 2015
Marziano and the trionfi are touched on in a rather basic "art" chapter, but what is is sure to intrigue everyone is this article:
"Il Sole ducale (1430): a proposito di una divisa viscontea", by Federica Cengarle
A wretched machine translation from a line in the beginning, but to give you a taste:
In July 1430 Filippo Maria Visconti commissioned his courtiers to give an oration to celebrate the effigy of the sun of his quadriga [four horse chariot], an image that takes up the classic representation of the Sol Invictus, already used by the emperors, as well as its Christian repositioning, and which he now wants to use for his sign.
The article delves into matter well beyond that. A must read.