I can see a lot of cool stamps there, mainly the Third Reich ones.
I can't tell you the first image is from Czechoslovakia.
The third image is a maximum postal of the Third Reich times. Here you can see that stamp: https://www.germanstamps.net/tr-rpst-1943-stamp/
There are many websites about stamps and topics related to stamps. What helps me a lot is searching on the internet for the text written on the stamps followed by any year that you can find there.
Let's take the first image as an example, I would look for: "stamps ceskoslovensko lenin 1924 1954"
One of the pages returned is this one: https://www.stampworld.com/en/stamp...ps/1970-1979
Your stamp is not there but is a good starting point.
I hope it helps.