American Stationer was the main trade publication for the stationery and fancy goods trade. There were a couple, with Geyers being the next biggest one, but American Stationer, by being located in NYC, was the largest and most well-connected. American Stationer published from 1873 up past 1928. There are tons of great ads and announcements of new products, etc... as well as reports of the various territories for salesmen and company news.
Geyer's Stationer was a little more focused on just the stationery trade, with a little on the fancy goods stuff. You tend to find longer articles in Geyer’s as well as a lot of attention to the activities of the National Association of Stationers, Office Outfitters, and Manufacturers, and their concerns, like the latest in window displays.
David Nishamura on his Vintage Pen blog has a list of online copies of most of the volumes. I've got links to his pages out on a page dedicated to these resources on my website. https://thesteelpen.com/2017/10/15/research-resources-for-steel-pens-american-stationer/