In the today's MMD 050726, Renaissance Le Corbeau says that he is
rather certain that the books Björn Isebaert asked about (MMD 050725)
are not for the Racca Piano Melodico.  Okay, he is absolutely right.

The original Racca Piani Melodici have 48 or 73 (75) notes.  Björn's
books are for the 30-note PM which was made by the German firm Wilhelm
Späthe (or Spaethe) in Gera.  Späthe made quite a number of Piani
Melodici in different cases under license from Giovanni Racca.

More information concerning the Piani Melodici was presented during
the 53rd Annual Meeting of the MBSI in 2002 and published in
C.F.C. Greinacher: Piano Melodico, A family of mechanical music
instruments; in "The Carousel Organ" Nr. 14, Jan. 2003, pp. 14-22.
Also in "The Music Box", Vol. 21, Nr. 3, 2003, pp.  89-97; and in
"Das Mechanische Musikinstrument", Nr. 90, 2004, pp. 7-19.

The Internet gives comprehensive information concerning Giovanni Racca
under http://www.pianomelodico.com/ 

Regards from Germany
Christian Greinacher