I have to admit, I've never searched for a book online using the books ISBN. So I look for pre-ISBN books... in the same way I look for ISBN books!

BH

The first LOTR paperbacks were published by Ballantine Books in October 1965. To look for early Ballantine editions, you need to specify the cover artist (Barbara Remington) and the printing date. I do not recall these ever being sold as a boxed set, though I could be mistaken. So Fellowship would be labeled "First Printing, October 1965", The Two Towers is labeled "First Printing: November, 1965", and I suspect (but am uncertain) that The Return of the King might be listed as "December, 1965" but in the event all were released in October, 1965 and the corrected date can be found in later printings.
However, you might not want to confine your search to just the First Printings, as some changes were made: for example, the first 3 or so printings of Fellowship had the Ring inscription upside down, later corrected; and changes were made in some of the Elvish sayings, I think around the time of the 8th printing.
But be sure to check the printing dates! Ballantine went through so many printings that after a hundred or so they started renumbering with "First Printing" again!
Collecting Ballantine editions can be quite interesting. I believe that the Tolkien Collection of Marquette University, Milwaukee, WI has a complete set of Ballantine, so they might be able to provide more detailed information.

dis wrote:
The first LOTR paperbacks were published by Ballantine Books in October 1965. To look for early Ballantine editions, you need to specify the cover artist (Barbara Remington) and the printing date. I do not recall these ever being sold as a boxed set, though I could be mistaken. So Fellowship would be labeled "First Printing, October 1965", The Two Towers is labeled "First Printing: November, 1965", and I suspect (but am uncertain) that The Return of the King might be listed as "December, 1965" but in the event all were released in October, 1965 and the corrected date can be found in later printings.
However, you might not want to confine your search to just the First Printings, as some changes were made: for example, the first 3 or so printings of Fellowship had the Ring inscription upside down, later corrected; and changes were made in some of the Elvish sayings, I think around the time of the 8th printing.
But be sure to check the printing dates! Ballantine went through so many printings that after a hundred or so they started renumbering with "First Printing" again!
Collecting Ballantine editions can be quite interesting. I believe that the Tolkien Collection of Marquette University, Milwaukee, WI has a complete set of Ballantine, so they might be able to provide more detailed information.

Pretty sure there was a boxed set (a fairly plain grey or green, I think?).