Association spokesman Charles Schmidt says electronic textbooks now represent just two to three percent of sales.

VOA: special.2009.09.03

Keyboard Cat, created by Charles Schmidt, first appeared in a YouTube video uploaded in 2007, showing a cat playing an electronic keyboard.

FORBES: Warner Brothers Sued For Infringing Cat Meme Copyright

The other firm in the mining race, Planetary Resources, has backing from several billionaire investors, including Google's Larry Page and Eric Schmidt, software executive Charles Simonyi and filmmaker James Cameron.

BBC: New venture 'to mine asteroids'

Others on the list include Norman Schmidt (330 years), Frederick Brandau (55 years), Charles Lewis (30 years), and Eduardo Maferrer (30 years).

FORBES: Professor Goes to Prison: Part II Pope, Milan and Hostetler