My dad purchased this Del Principe accordion in the early 1950s/late 1940s. It is stamped "Made in Italy #728" on the back. The word "Master" is also printed above the keys. I can't find much information about Del Principe online, except that it was a store in Chicago near where my dad lived. I found a site that said the Del Principe accordion store distributed Dallape accordions. Is this a Dallape that is branded Del Principe? Any information would be useful. Additionally, I am looking to sell it and do not know where to start. I appreciate any advice. Thank you!