Swedish patent 1873: The Takygraf
- A notice in the Swedish periodical, Teknisk Tidskrift, telling about the patent about the Takygraf in the name of RMH and C. P. Jürgensen from 4.th of October 1873. All copies are made by Jørgen Malling Christensen
- One of the drawings of the Takygraf that was included in the patent application
- Patentet ble også presentert i Teknisk Tidskrift 1873.11.27.
