Joe Shuster hand drew Superman logos until the classic Ira Schnapp logo appears with Superman (DC, 1939 Series) #6 (September-October 1940).
Joe Shuster's signature is at the bottom left corner of the cover and is usually cut off in part or in full on many copies of this issue.
Frontispiece. Paul Cassidy art credits added by Craig Delich.
The first story with Luthor was in Action Comics #23 (cover date April 1940). Superman asks "Who is Luthor?"
This is the second Luthor story. Luthor says "We encounter each other once more".
However this issue may have gone on sale before Action Comics #23. In their copyright registration, Detective Comics, Inc. said Action Comics #23 was published Feb 23, 1940. An in-house ad said Superman #4 would go on sale Feb 15; the copyright registration said that it was published Jan 23. Officially, per DC Comics web site, Luthor's first appearance is in Action Comics #23.
One panel promotional advertisement for the Spectre series in More Fun Comics (DC, 1936 series) at the end of the story, with art by Bernard Baily.
Lettering credit and information by Craig Delich.
One panel promo for the Sandman, appearing in Adventure Comics, is found at end of the story, with art by Creig Flessel.
At the bottom of the first column on page one is an advertisement for "The Genuine Junior Guitar for You!" and at the bottom of the last column on page two is an advertisement for "Real Live Canary for You" both from selling seeds for the Lancaster County Seed Company of Lancaster, Pennsylvania.
Information and art credits by Craig Delich.
One panel ad for Batman appearing in Detective Comics appears at the end of the story, with art by Bob Kane.
Superman logo is a one-off hand-drawn version by Joe Shuster, though now very close in design to the one on the cover of Superman #1.
Some information added by Craig Delich.