Rickenbacker International Corporation
The website outlines the early history of the company as well as the guitars. It is reliable because it is the corporations website as shown on the bottom of the page with the registered trademark.
Lemelson Center for the study of invention and innovation
This website is operated by the Smithsonian National Museum, which is a reputable source of history. The website provides information on actual artifacts found at the Smithsonian National Museum of American History.
National Music museum
The National Music Museum created this website and offers insight to the history of music. Like the Smithsonian website, the National Music Museum puts up information about actual artifacts they house in their museum.