Below is a list of technical articles about the Recordo expression
player piano system, written by Bob Billings and published in the
AMICA Bulletin in the early 1970s.

Ref. https://www.amica.org/MembersOnlyProtected/MembersOnlyMenu.htm 
https://docs.google.com/spreadsheets/d/12PXkn9-zRIqrbxaJ0ClUNThQ9ASWgjZGaDDwUxidop8/edit?gid=0#gid=0 

Robbie Rhodes, MMD

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RECORDO BANNER FLIES AGAIN
Bob Billings
AMICA Bulletin Vol 8. No. 1, January 1971

RECORDO BANNER FLIES AGAIN
Bob Billings
AMICA Bulletin Vol 8. No. 2, February 1971

PART II: RECORDO BANNER STILL WAVES
Bob Billings
AMICA Bulletin Vol 8. No. 3, March 1971

RECORDO BANNER STILL FLIES: PART III THE "B" SYSTEM
Bob Billings
AMICA Bulletin Vol. 8 No. 5, May 1971

RECORDO BANNER STILL FLIES PART IV: THE "C" RECORDO
Bob Billings
AMICA Bulletin Vol. 8 No. 7, July 1971

RECORDO BANNER STILL FLIES PART V: RECORDO ROLLS
Bob Billings
AMICA Bulletin Vol. 8 No. 10, October 1971

RECORDO BANNER STILL FLIES
Bob Billings
AMICA Bulletin Vol. 9 No. 7, July 1972

"C" RECORDO CONFIRMED
Bob Billings
AMICA Bulletin Vol. 10 No. 10, October 1973