It's in the 1923 ATF Specimen book. I can't insert an image here, but you can find it by going to Google Books and searching for
ATF Catalog 1923
It's on one of the sample pages.
I also tried to attach an image of the google-books excerpt that found that source. It's from "The Secret History of Letters" by Simon Loxley. It states that there's a specimen in the 1923 edition of the ATF catalog. Still can't insert, so here's the text rewritten:
"His [Benton's] other durable face was fifty years ahead of its time. Designed in 1914, Souvenir was offerec to the trade in the early 1920s. It appears in the 1923 specimen book, but curiously, given ATF's belief in the type family, it came in one weight only, with no italic. This apparent lack of confidence in the design was reflected by market response, and Souvenir died an unlamented death. However, in 1967 a company called Photo-Lettering revived it for one of its accounts, and two years later the face achieved high profile when a redrawn version, known as Eastern Souvenir, was created for the new identity for Eastern Airlines. Souvenir is a face that is intractably rooted in style to a particular era, although one a half-century after its creation. It is a quintessential alte 1960s and 1970s typeface, informal, with full rounded character shapes and rounded serifs, a laid-back Cheltenham."
[I sure wish that image insert was working]
- Herb


