This excellent book covers (from 1943 thru 1957) a section of the pin-up calendar genre, the Artist's Sketchpad. The calendar publishers of the day hit on the bright idea of having additional sketches and paintings surrounding the main pin-up image. This had the added advantage of not requiring the artists to think of humorous situations in which to place the 'girl next door'. Leader of the pack, Gill Elvgren, didn't do sketch pad calendars, he could always think up some credible situation to show a gorgeous female with a raised skirt, he does have some paintings included though.
The book wisely shows each complete calendar page, so you can see the names and addresses of the companies that bought these give-aways by the million (those were the days when phone numbers had a bit of character, like MUrray Hill 2-4090, DEarborn 2-1935 or HYacinth 7-3595). Each monthly chapter has, on average, thirty-two pictures displayed on light colored pages and some pages have displays of those terrible four-line poems that seemed to be a requirement of any respectable girlie calendar.
The introduction mentions ten artists who painted most of the pin-ups shown but the book has a major omission in that none of the pictures are credited. Artists like Moran, Munson, Elliot, Mac Pherson or Elvgren have signatures you can recognise on the paintings but I think it would have been helpful if the all the names were printed by each picture. However, here's an idea, get a copy of the stunning 'Great American Pin-up' (ISBN 3-8228-1701-5) and spend a pleasant hour or so using the nine hundred pictures (by sixty-one artists) to identify all the paintings in 'Calendar Girl'.