My Collection of Vintage Advertising Labels

About a year ago I came across a set of four books containing vintage Alcohol/Spirits advertising labels (over 350 different labels), and I believe they're either salesman samples or perhaps print files... I'm really not sure.

The books are a dark brown/green color with about 20 sheets in each, and they're bound with a cover of thick paper/card stock. The labels are spot pasted on both front and back sides of each sheet... A couple of the books only have 3-6 pages with labels, while the other two are full or almost completely full. All four of the books are from the St. Louis Lithographing Co (they all have the logo on the front cover), and on the inside of one of the books was some writing with the date "June 1942," so I'm guessing the labels are from the 1930's to 40's. I also found a sheet of letterhead stationary tucked inside with typed instructions listing ink formulas and how to mix the chemicals to create different colors for the printing process.

The majority of labels are for various Whiskey brands and distilleries, including Jack Daniels, but there are also Gin, Vodka & Wine labels (also from various brands/distilleries). They're all in great condition, maybe only a few that may have some slight blemishes due to age/wear.

I’ve tried researching all over the internet for something similar to what I have, but I haven’t been able to find anything... I’ve tracked down info on salesman sample books for match covers, fruit crate labels, greeting cards & cigars, but I haven’t seen a single picture, auction or post referencing a salesman sample book of alcohol labels... I’m sure they probably exist, but all I could find were auctions or listings for groups of loose or single alcohol labels, so I’m having difficulty finding out any historical/background information, as well as rarity (if any).

These books and labels are so fascinating to me because they represent an era long past (that I wish I lived in!), and I appreciate the level of detail and design that was put into each of them. If someone can tell me more about them, and whether or not this is a rare collector's item, that would be awesome!!