| Business | Phone |
| William Rudman Assoc 10 Fawcett St, Cambridge 2138 | (508) 893-9900 |
| United Investigative Svc 124 Mount Auburn St, Cambridge 2138 | (617) 576-5762 |
| Thorndike Investigations 230 Monsignor Obrien Hwy, Cambridge 2141 | (617) 868-8009 |
| Strategic Research 49 Fayette St, Cambridge 2139 | (617) 497-6700 |
| Control Security Svc 215 1st St # 215, Cambridge 2142 | (617) 494-1999 |
| International Service Conslnts 255 Bent St, Cambridge 2141 | (617) 497-4587 |