http://members.lycos.co.uk/brackenrigg/concertina.html

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bass: 19 buttons

            E C       A A#      C# D#      A G        G# A#


       C G       G B      C D        E F        G A        F F


  B D      D F#      G A       B c       d e      f# g#


                             D# E                               F C


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treble: 19 buttons

         C# d#     a g      g# a#    c#' a#     f# d'


  d# c#      c B       e d       g f       c' a      e' b      f e


      d  A       g f#       b a        d' c'    g' e'     a g#


                                 f#' f'


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