Back in 2017, five of the six 1977 Stuart Pharmaceutical calendars from the series numbered DM-73301 to DM-73306 were shared:

1. June: Escape from Prison when Manacled in Handcuff and Irons (HHCE Collection)
2. July: The Celebrated Straitjacket Release (HHCE Collection)
3. August: The Challenging Release From Wet Sheets (John Cox Collection)
4. September: The Perilous Escape From the Spanish Maiden (HHCE Collection)
5. October: The Spectacular Release From the Cannon (HHCE Collection)

Each featured Spectacular Houdini Feats and original artwork by James Barkly. At the time, we didn’t know what the number 6 (DM-73306) calendar was, but we do now.

It is for the The Daring Underwater Escape from a Nailed Packing Box and covers the month of November and December.
Stuart Pharmaceutical’s also created six 1978 Houdini calendars, of which five ot them I will be sharing at later dates; the September/October 1978 calendar still alludes me.