Are there any novels containing 40s-50's vocabulary and speech? I know, look for books written in the 40's and 50's, but which ones capture the way average citizens spoke?
Just like present day, people spoke in all sorts of ways. Slang in one place wasn't known in another, accents, there are so many variables. Add to that the fact that there wasn't as much travel as there is now, or social media, and the pockets of unique speech become even more specific.
This was written in the 20s or 30s. So it should be similar...desu senpai its not really that different