Inherited Set Of Wimmer Engravings - Progressive Series And Single Stamps

I am hoping for some assistance with a few original engravings for stamps by Georg Wimmer that I inherited. One is a progressive series of Johann Strauss, while the others are of composers. There is also one is of JF Kennedy. I am not a collector and so feel someone else would appreciate these more than I do. Could anyone offer guidance on where I could take something like this and on whether they have any monetary value? Any insight would be greatly appreciated.

There are lots of these around.
I purchased mine (singleton) for $5
I have seen Kennedy similar to yours (In puce / claret) realise £110 ($140 US) 2005

Lot included Kennedy in 3 colours, Imperforate on unwatermarked card,
3 similar perforate and gummed, unwatermarked.

These were sold in your neck of the woods, Gosvenor Philatelic Auctions
399 The Strand London.
Good Luck.

Thank you very much for the information, that is really helpful!

Apologies,
make that Grosvenor Philatelic Auctions.
(But you may have known that)

...and again my apologies, was 2015 not 2005

FYI
https://stampengravers.blogspot.com...sponses.html

Again thank you so much rod222. I had managed to figure out that it was Grosvenor (or rather Google had :) but I appreciate you taking the time to send me clarification, as well as to send me the blog link, which speaks to both sets of "essays" I have. I have had these items for a long time now and it is really great to finally understand what they are and where they come from!