The ISBN was invented in 1970. Your books don't care

The ISBN, invented in 1970 to organize mass-market publishing, has become the default identifier in modern book cataloging software despite being entirely unsuitable for historical books and non-mainstream publishing. Libraries and collectors working with pre-ISBN materials or rare books rely on specialized cataloging systems like ESTC and VD16/17/18, which are far more precise but ignored by most contemporary software that treats the ISBN as the primary organizing principle.