In 1915 the steno books of the day did not have a spiral at the top, most of the ads and other pictures and illustrations show a tablet with the pages flipped back.
Here's an ad for a stand for the notebook:
However, this ad in a 1915 shorthand magazine, had a notebook with two rings on the top. I thought it might be an idea for those who have loose leaf paper but want to keep it together. These were also loose leaf so you could add or remove paper.
Here's another ad for it, showing the hard bound top and back.
"Gregg Shorthand had achieved the most extraordinary success ever attained by any system in the history of shorthand." John Robert Gregg, 1922
Amazon does sell a bundle of steno books (link). The reviews do mention that they don't have stiff backs, so if you plan on writing on your lap or in your hand, then you may want to find another one. It wouldn't ship to my PO Box address, so I deleted the order. But it's an option for those who need a bunch for studying. They are white sheets of paper, which isn't bad, but if you plan on studying for long periods of time, the green tint is what you really want. I sometimes pick up one when I'm at the dollar store to have on hand, they're the same type of back (not stiff), white paper also, and a bit more then this bundle so that's why I tried to order this bundle.
Check out the similar items as you might want something different. Or even just search for "steno pad".