Copper engraving, contemporary hand-colored, 375 x 485 mm. Map of the Bishopric of Trento from Lake Garda to Bolzano. Janssonius was, first in collaboration with his brother-in-law Henricus Hondius and then, from 1638, on his own, the most important competitor of the Blaeus, inspiring and standardizing their production, so much so that Blaeu, also a Jansson by birth, was forced to adopt a pseudonym to differentiate his work. Good copy with two restored marginal tears, sheet a little browned