Patents
A. Springer 1885 Patent
A. Springer 1885 Patent
Springer_1885_US310545.pdfA. Fries 1891 patent
A. Fries 1891 patent
Fries_1891_US452371.pdf© R. Paselk 2013, Last modified 31 December 2020
Springer_1885_US310545.pdfFries_1891_US452371.pdf© R. Paselk 2013, Last modified 31 December 2020