books%3Fid=d7zOviXnbSYC&printsec=frontcover&dq=Jan+Sapp&hl=de&sa=X&ved=0ahUKEwjZ0Mfh8YfYAhUB2KQKHYrXDrwQ6AEIRTAD%23v=onepage&q=Jan%20Sapp&f=false

books%3Fid=d7zOviXnbSYC&printsec=frontcover&dq=Jan+Sapp&hl=de&sa=X&ved=0ahUKEwjZ0Mfh8YfYAhUB2KQKHYrXDrwQ6AEIRTAD%23v=onepage&q=Jan%20Sapp&f=false

https://books.google.de/books%3Fid=d7zOviXnbSYC&printsec=frontcover&dq=Jan+Sapp&hl=de&sa=X&ved=0ahUKEwjZ0Mfh8YfYAhUB2KQKHYrXDrwQ6AEIRTAD%23v=onepage&q=Jan%20Sapp&f=false
Otto Kandler
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books%3Fid=d7zOviXnbSYC&printsec=frontcover&dq=Jan+Sapp&hl=de&sa=X&ved=0ahUKEwjZ0Mfh8YfYAhUB2KQKHYrXDrwQ6AEIRTAD%23v=onepage&q=Jan%20Sapp&f=false

https://books.google.de/books%3Fid=d7zOviXnbSYC&printsec=frontcover&dq=Jan+Sapp&hl=de&sa=X&ved=0ahUKEwjZ0Mfh8YfYAhUB2KQKHYrXDrwQ6AEIRTAD%23v=onepage&q=Jan%20Sapp&f=false