Beginning with the July 1935 issue, readers were treated to “The Doc Savage Method of Self-Development.” Just like the main stories, these are attributed to Kenneth Robeson. The list includes both physical and mental exercises. Readers are told that Doc Savage’s diligent and consistent use of these methods are responsible for his abilities. This series continued for twenty-three consecutive issues, ending with the May 1937 issue.
Listings for “The Doc Savage Method of Self-Development.”
Jul-1935 (Exercises 1-7)
Aug-1935 (Exercises 8-13)
Sep-1935 (Exercises 14-19)
Oct-1935 (Exercises 20-25)
Nov-1935 (Exercises 26-31)
Dec-1935 (Exercises 32-38)
Jan-1936 (Exercises 39-44)
Feb-1936 (Exercises 45-50)
Mar-1936 (Exercises 51-55)
Apr-1936 (Exercises 56-60)
May-1936 (Exercises 61-63)
Jun-1936 (Exercises 64-67)
Jul-1936 (Exercises 68-72)
Aug-1936 (Exercises 73-77)
Sep-1936 (Exercises 78-84)
Oct-1936 (Exercises 85-89)
Nov-1936 (Exercises 90-95)
Dec-1936 (Exercises 96-98)
Jan-1937 (Exercises 99-104)
Feb-1937 (Exercises 105-109)
(Exercises 110-119) –Missing!
Mar-1937 (Exercises 120-124)
Apr-1937 (Exercises 125-129)
May-1937 (Exercises 130-131)
The exercises end with #131, but there is a problem. The last exercise in the February 1937 issues was #109. The next issue, March 1937, started with exercise #120. Clearly someone made a mistake in the sequencing. Hence there are a total of 121 exercises.
Just who wrote these exercises? Well, the answer is below.
The Street & Smith records are held at the Special Collections Research Center at Syracuse University in New York. I submitted a request for copies of the Manuscript Tracer Cards used for information on story author, pen name, date of payment and amount, along with publication data. This was in September 2021. The items came shortly thereafter but lingered in my desk drawer. There were twelve cards detailing information on the Doc Savage exercises. Ten were attributed to Paul Rothenberger and one to Paul Rothenberg. One card was attributed to Morris O. Jones who was an assistant editor working for John Nanovic.
Tallying up the individual listings from each Manuscript Voucher forma the result shows that Paul Rothenberg is credited with 117 exercises. Adding in the four exercises written by Morris Jones matches the published total of 121 exercises.
The last question is what is the correct name? Is it Rothenberger or Rothenberg.
My money goes on Paul Rothenberg which is explained in another article. 
May 10, 1935
MSV# 22571
$21 paid to Paul Rothenberger for seven exercises.
They are listed 1 -7 at $3 each.
Appeared I July 1935
May 24,1935
MSV# 22865
$21 paid to Paul Rothenberger for seven exercises.
They are listed 8 – 14 at $3 each.
Appeared in August 1935
June 28, 1935
MSV# 24222
$15 paid to Paul Rothenberger for five exercises.
They are listed 15 – 19 at $3 each.
Appeared September 1935
September 13, 1935
MSV# 25590
September 20, 1935
MSV# 25416
This sheet has two invoice numbers written on it and two dates. The layout is confusing, but the handwriting has distinct differences resulting in the date and number assigned here.
The invoice shows a list of amounts totaling $123 paid to Paul Rothenberger. This would be forty-one exercises at $3 each.
The appearances show a dollar amount for each issue:
October 1935 – $18 (six exercises)
November 1935 – $18 (six exercises)
December 1935 – $21 (seven exercises)
January 1936 – $18 (six exercises)
February 1936 –$18 (six exercises)
March 1936 – $15 (five exercises)
April 1936 – $15 (five exercises)
December 6, 1935
MSV# 27699
$45 paid to Paul Rothenberger for fifteen exercises at three dollars each.
They are listed 46-50
Appearances are not listed.
March 27, 1936
MSV# 30646
$45 paid to Paul Rothberg for exercises 61 – 75 totaling fifteen exercises.
The appearances show a dollar amount for each issue:
May 1936 – $9 (three exercises)
June 1936 – $9 (three exercises)
July 1936 – $18 (six exercises)
August 1936 – $9 (three exercises)
July 17, 1936
MSV# 33665
$21 paid to Paul Rothenberger for seven exercises.
Appeared September 1936
August 28, 1936
MSV# 34849
$15 paid to Paul Rothenberger for five exercises.
Appeared in October 1936
September 18, 1936
MSV# 35463
$39 paid to Paul Rothenberg for thirteen exercises.
November 27, 1936
$24 paid to Paul Rothenberg for eight exercises.
Note: October appears here and on MSV# 34849 above. This may indicate a double payment.
Appeared in the following issues.
October 1936 – five exercises used.
November 1936 – six exercises used.
December 1936 – three exercises used.
January 1937 – six exercises used.
February 1937 – one story used.
November 22, 1936
MSV# 37497
$15 paid to Paul Rothenberg for five exercises.
(Three used)
Appeared in March 1937.
December 11, 1936
MSV# 37985
$12 paid to M. O. Jones for four exercises. Morris Ogden Jones was an assistant editor at Street & Smith working for Doc Savage editor John Nanovic.
Appeared in February 1937 issue.
January 8, 1937
MSV# 38899
$27 paid to Paul Rothenberg for nine exercises.
Appears in April 1937 – five used.
Appears in May 1937 – four used.