Citada por|
| US4194181 | 28 Nov 1977 | 18 Mar 1980 | Efficiency Systems, Inc. | Hotel room status monitor and power control system | | US4254404 | 13 Sep 1978 | 3 Mar 1981 | Kramor Industries Ltd. | Paging and servicing system | | US4378551 | 5 Dic 1980 | 29 Mar 1983 | Motorola, Inc. | Radio signal receiving apparatus with a security circuitry | | US4758819 | 7 Feb 1986 | 19 Jul 1988 | Aica Kogyo Co., Ltd. | Keysensor | | US5032834 | 12 Feb 1990 | 16 Jul 1991 | Sara E. Kane | Status display system | | US8149104 | 24 Jun 2009 | 3 Abr 2012 | | Room management system |
|