English: From Electronics magazine, 1934, an information diagram in the shape of a tree displaying many points of development and differentiation in vacuum tube technology during the 51-year span of 1883 and 1934. The points of divergence indicated by branches on the tree express the historical relationships between many different kinds of tubes that share common origins, including X-ray tubes, Cathode Ray tubes, and tube types used for different kinds of sound amplification applications.
Date
Source
Electronics magazine, May 1934, page 147. In the holdings of the Prelinger Library.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.