My great uncle gave me a Hohner Marca Registrada instrument, made in Germany, with a one-row, 10 buttons keyboard and 4 bass buttons, in a beautiful golden wood box. I believed this instrument to be a Concertina, but from your wonderful forum and websites, I now am learning may be a Diatonic Melodeon. Can anyone help w/info about what, where and when this instrument was built and what its value might be. Thanks