Automatically validate and format ISBNs

Question

Is there any way to get Biblatex to automatically validate and format ISBNs? That is, I would like to be able to enter a field such as

isbn = {9789549090666},

in my .bib file—not worrying about the presence or proper placement of hyphens—and have Biblatex render this as "ISBN 978-954-90906-6-6" when I print the bibliography with \printbibliography. It would also be useful if Biblatex could first validate the ISBN and, if it's an older ISBN-10, convert it to ISBN-13.

If there's no easy way of doing this in Biblatex, is there perhaps an external program I can run on my .bib file to do the validation and formatting? All I've found so far are online tools, and some of them improperly group the digits of the ISBN. (For those that aren't aware, while ISBNs have a fixed number of digits, the lengths of the hyphen-separated groups are variable.)

Answer 1

Please try biber 2.2 (along with biblatex 3.1). The --validate-datamodel option will report on invalid ISBNs. The new options --isbn10 will force ISBNs to 10-digit format and --isbn13 to 13-digit. --isbn-normalise will format with hyphens in the correct places.

The module which does this in Biber has a database of ISBN numbers which is updated with new releases of the module.

Answer 2

The main problem with recreating the hyphens is the ISBN itself.

It is build as number with 13 digits:

ISBN: prefix - country - publisher - book - check number

for example: 978 - 3 - 86680 - 192 - 7. The prefix has 3 digits, the check number 1, the country number 1, total 5. You have 8 digits for publisher and book together.

So we have now recreated: 978-3-86680192-7.

And here is the problem, you have to know all publisher numbers to recreate the hyphen between publisher and book. There are publisher with a 7 digit number and only one numer for books (that publisher can only produce maximaum 10 books), others have 3 digits for the publisher and 5 for the book number.

That's the reason I would not try to recreate the lost hyphens with LaTeX. Better use one of the named web sites in the comments to get the lost hyphens back and add them to your bib entry.

Then you can use the method from question Calculating checksum (see comment of @egreg).

To validate a ISBN you need to know if the publisher and book number are valid (current publisher or no longer operating publisher?, was the book available?) and if the check number is valid.

Older ISBN numbers (10 digits) can be build to current 13 digit ISBN numbers by just adding 978-first. Now you have to recalculate the last check number and use it. See for example both ISBN for the LaTeX companion: ISBN-10: 3827316898 and ISBN-13: 978-3827316899. The bold part is equal. With hyphens the ISBN is: 978-3-8273-1689-9 with 3 for German, 8273 for Pearson Studium, 1689 for book "Der LaTeX-Begleiter".

Answer 3

Assuming the ISBN-13 starts with 978, the following plain TeX code will generate the correct check digit (substitute the nine digits following 978 in this example, where zeros are given):

\newcount\isbncount
\newcount\scratchcount
\def\isbncalc#1#2#3#4#5#6#7#8#9{%
    \isbncount=38%total yielded by initial 978
%       i.e. 1x9 plus 3x7 plus 1x8
    \scratchcount=#1 \multiply \scratchcount by 3
    \advance \isbncount by \scratchcount
    \advance \isbncount by #2
    \scratchcount=#3 \multiply \scratchcount by 3
    \advance \isbncount by \scratchcount
    \advance \isbncount by #4
    \scratchcount=#5 \multiply \scratchcount by 3
    \advance \isbncount by \scratchcount
    \advance \isbncount by #6
    \scratchcount=#7 \multiply \scratchcount by 3
    \advance \isbncount by \scratchcount
    \advance \isbncount by #8
    \scratchcount=#9 \multiply \scratchcount by 3
    \advance \isbncount by \scratchcount
    \the \isbncount}
\isbncalc{0}{0}{0}{0}{0}{0}{0}{0}{0}
\bye

At least, that will yield the number which will give the check digit when modulo 10 is applied (so e.g. if 187 is produced, the check digit is 3, which is the number required to round up to the next multiple of 10). Clever people on here might be able to take this further so that the actual check digit is produced.

For correct generation of hyphens I would suggest https://www.loc.gov/publish/pcn/isbncnvt_pcn.html (which will also convert between ISBN-10 and ISBN-13). The digit after 978 is nearly always zero, surrounded by hyphens, and the check digit is preceded by a hyphen, but the position of the other hyphen isn't (AFIK) produced automatically by a mathematical operation.