Here is a look at the history of the Sony Walkman, a device created in 1979 by Masaru Ibuka and Akio Morita that ushered in the era of portable music.
Sony Walkman - Design Museum
10 Facts About the History of the Sony Walkman That Bring you Back, walkman
Walkman - Wikipedia
A history of Sony's successes and failures, Sony
The History of Sony Walkman
SONY Walkman II (1981)
10 Facts About the History of the Sony Walkman That Bring you Back in Time - Catawiki
Walkman Story: The Early Years of the Iconic Personal Cassette Player
Walkman - Wikipedia
List of Sony Walkman products - Wikipedia
Sony Group Portal - Product & Technology Milestones−Personal Audio