/// <summary> /// Converts the ISBN13 to ISBN10. /// </summary> /// <param name="isbn">The isbn.</param> /// <returns></returns> internal static string ConvertISBN13ToISBN10(string isbn) { // Remove the prefix isbn = isbn.Substring(3, isbn.Length - 3); // Switch the checksums var checksum = Spec.CalculateChecksum10(isbn); isbn = isbn.Substring(0, isbn.Length - 1); isbn += checksum; return(isbn); }