| Business | Phone |
| Central Maryland Research 11975 Homewood Rd, Ellicott City 21042 | (301) 596-9413 |
| Mack Research & Writing 3565 Ellicott Mills Dr, Ellicott City 21043 | (410) 461-0022 |
| Research & Design Svc Inc 3525 Ellicott Mills Dr, Ellicott City 21043 | (410) 465-7833 |