ISBNiser: Validate, Convert, and Link to ISBN-10 and ISBN-13 Codes

International Standard Book Numbers (ISBNs) provide a unique identification for each edition of a published book, and are essential when citing works or linking to them on on-line booksellers. This command line utility, implemented in Perl, validates both older ISBN-10 and current ISBN-13 formats, converts between them, and creates links which can be used to order the book from Amazon, optionally crediting the purchase to an Amazon Associates account.