Russell Kent wrote:

Paul,
Could you explain the text in the second image? (Hoerner on
ring-type radiators.)  I don't get the letter references, the last
type (d) is never mentioned and has 2 Cda's.

Russell Kent

Russell and everybody else. This is the complete list of references.
Let me know if you have any luck finding these. Library  of Congress
is my best guess.

Paul Lamar
 
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