| Number | Name | Date | Kind |
|---|---|---|---|
| RE. 34314 | Forsberg | Jul 1993 | |
| D. 235570 | Barton | Jun 1975 | |
| D. 284308 | Risi et al. | Jun 1986 | |
| D. 298463 | Forsberg | Nov 1988 | |
| D. 380560 | Forsberg | Jul 1997 | |
| D. 381086 | Forsberg | Jul 1997 | |
| D. 384168 | Stevenson | Sep 1997 | |
| 1831858 | Haggard | Nov 1931 | |
| 2172051 | Robbins | Sep 1939 | |
| 2319203 | Branham | May 1943 | |
| 5409325 | Wu | Apr 1995 | |
| 5479746 | Mannonen | Jan 1996 | |
| 5620283 | Walter | Apr 1997 | |
| 5678958 | Rossi | Oct 1997 | |
| 5702208 | Hilfiker et al. | Dec 1997 | |
| 5827015 | Woolford et al. | Oct 1998 |
| Number | Date | Country |
|---|---|---|
| 538726 | Mar 1922 | FR |
| 693797 | Jul 1953 | GB |
| Entry |
|---|
| “Soundblox”, p. 2 from Sweet's Architecture File, 1970.* |
| Modular Concrete Block, Paving Stone, Jun. 1984.* |
| “Proudfoot Architectural Acoustics” Sweet's General Building & Renovation Catalog File, 1993.* |
| Besser Parts and Equipment Catalog, “Chimney Block”, p. 11.* |
| Decor Innovative Concrete Systems—“STEP STACKER” brochure no date. |
| Borgert Products, Inc. advertising entitled, “Steps Made Eady! With Stair Stackers”. |