"The History of the Edison Disc Phonograph ." Memory Loc. N.p., n.d. Web. 26
     Mar. 2010. <memory.loc.gov...>.

This website talks about how the shift from wax cylinders to discs came about. One of Edison’s competitors, Columbia records, had already been developing discs. The rising popularity of the disc led to the Edison Company to eventually releasing their own form of the disc. It goes into detail about what materials were used for the disc and how the two designs differed from each other.