| Business | Phone |
| General Learning Communication 900 Skokie Blvd 200, Northbrook 60062 | (847) 205-3000 |
| Chesley Limited 3170 Macarthur Blvd, Northbrook 60062 | (847) 562-9292 |
| Vocational Testing Inc 2970 Lake Placid Ln, Northbrook 60062 | (847) 559-0061 |
| Hfn Fairchild Publications 707 Skokie Blvd, Northbrook 60062 | (847) 291-4307 |
| Prime Publishing Inc 3400 Dundee Rd, Northbrook 60062 | (847) 205-9375 |
| Timesfour Inc 959 Red Haw Rd, Northbrook 60062 | (847) 272-5944 |