Emblemata: Handbook Of Symbolic Art Of The 16th & 17th Century (1967, HC) German
This is a fantastic academic reference book "Emblemata: Handbuch zur Sinnbildkunst des XVI. Jahrhunderts" by Arthur Henkel and Albrecht Schöne. Topic: It is a comprehensive German-language handbook focusing on the art of emblems and symbolism from the 16th and 17th centuries.