Here is the 1956 Riverside edition, measures about 5 by 8. Having attended highschool in the 1960's I had several classic books printed by the Riverside Press in Boston, listed as Riverside Press Cambridge.
Notably, I had Jude the Obscure. Never touched it in highschool. That book I choose to read the summer I got laid off from Norton Company, 1988.
By the swimming pool at the country club, while I was working on buying the first of several businesses I would buy over the years, I read Jude the Obscure... Ykes, what was I thinking? Dark, depressing, wonderful... I ended that summer with a nice tan.
Anyways I digress, the feel of these books captivated me and I bought anything printed in this series that I ran across in my travels. Currently, in a different section of the library I have a dozen or so titles, alas not Jude the Obscure. I tied up about a half dozen Riverside Press books neatly with hemp string and put that package aside in one of the moves I made after the divorce. Somewhere, somehow that package went missing and I have never seen it or Jude the Obscure since.