Found the leporello above yesterday at the flea market.
The book with children's songs is another lovely one from my childhood, but I'm not as old as it seems to be ;) The publishing date is 1961 ... maybe my parents got this book second hand as well, have to ask them, where it comes from.
The illustrations are by children's book author and artist Marlene Reidel. Just could not resist to order this one here (you can never have enough children's books, right?) - so stay tuned for one more, I will show you some pages here.
(Behringer/Feist/Mosbacher: Singen, Spielen, Tanzen, C. C. Buchners Verlag, 1961)