ICONCLASS
49L65 seal, stamp
The institution has not been identified, but there are two copies at Oxford with this stamp . See https://data.cerl.org/owners/00014800
It is the stamp of the Convento dei frati minori riformati di Santa Maria del Giardino (Milano). https://www.lombardiabeniculturali.it/archivi/soggetti-produttori/ente/MIDB0008DD/ You can find the reference in Sandro Pirovano, Il Convento Di Santa Maria Della Misericordia in Missaglia, p. 112, n. 14 and in Giancarlo Petrella, L’oro di Dongo, Firenze 2012, pp. 69-70 with a picture of the title page of a book where the attribution of the stamp is also confirmed by a manuscript note. In our library (Biblioteca Salita dei Frati Lugano), we found an exemplar whit the same stamp: http://aleph.sbt.ti.ch/F?local_base=SBT01&func=find-c&ccl_term=SYS=000869114, if you need I can send the picture.