| Digest Nr | Subject and Author |
 |
| 2022.01.22.02 |
Roll Boxes for Arburo, Bursens, Popper, Eich, Etc., from Roger Wiegand |
| 2021.06.06.01 |
Popper "Stella" Reproducing Piano of 1908, from Uwe Gernert |
| 2021.05.31.02 |
Popper "Stella" Reproducing Piano of 1908, from Jim Miller |
| 2017.12.14.01 |
Ibach Pianos Delivered to Welte, Hupfeld & Popper, from Marc Widuch |
| 2012.02.10.03 |
Popper Roland "Swanee Whistle" Operation, from Dale F. Rowe |
| 2012.02.09.01 |
Popper Roland "Swanee Whistle" Operation, from Roger Wiegand |
| 2011.10.18.03 |
Seek Popper Konzertist Orchestrion Rolls, from Wayne Finger |
| 2011.05.29.05 |
FS: Popper Piano Spool Box & Action, from Donald MacKenzie |
| 2011.03.28.02 |
Popper "Roland" Orchestrion, from Bernt Damm |
| 2010.10.12.14 |
Popper Orchestrion Note Ranges, from Wayne Finger |
| 2009.03.13.04 |
Popper Gladiator Recording on San Sylmar CD, from Jack M. Conway |
| 2009.02.20.06 |
Seek Popper Gladiator Recording, from Brian Smith |
| 2006.08.06.02 |
Seek Rolls for Popper Welt Konzertist Piano, from Wayne Finger |
| 2006.06.30.07 |
FS: Popper Welt Konzertist in Seattle, from Eric Shoemaker |
| 2003.06.26.05 |
Source of Popper Rolls, from Jurgen Goering |
| 2003.06.25.12 |
Popper Mechanism Plays Konzertist Rolls, from Carl Kehret |
| 2002.09.08.06 |
FS: Popper Welt Piano Konzertist, from Philip Jamison |
| 1999.04.20.12 |
FS: Popper Konzertist & Phillips Duca, from Dirk Tiedt |
| 1996.04.22.06 |
Popper Valves, from Philip Jamison |
| 1996.04.19.05 |
Popper Konzertist, from Philip Jamison |
| 1996.04.15.14 |
Popper Valves, from Philip Jamison |
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