Book with LCCN but no ISBN

[ElizaChr]

Hello,

 

I 'm a new member and really happy to see how many people here share the same passion about books! I was wondering if you can help me regarding the following.

 

I recently bought Erich Segal's "Love Story", first edition, first printing, Harper and Row. It was one of my favourite books about 20 years ago and I still love it! The book has got a Library of Congress number but no ISBN. However, there is an ISBN stated for this edition on websites selling used books. How can I find the ISBN of the book I have? Shouldn't it have an ISBN printed? I was thinking about buying one more copy with a better dust jacket, so it would be useful to know the ISBN, right?

 

Thanks a lot!