| Author: | American School of Correspondence |
| Subject: | TK, Telegraph, Telephone |
| Format: | Text |
| Date issued: | 2005 |
| Language: | English |
| Publisher: | Project Gutenberg, |
| Rights: | Public domain in the USA. |
| Download link: | Cyclopedia of Telephony and Telegraphy, Vol. 1 : A General Reference Work on Telephony, etc. etc. [electronic resource] / American School of Correspondence |