Modül:ISXN denetle
-- This template is a copy of the ISXN validation code from Module:Citation/CS1
-- which allows for validating ISBN, ISMN, and ISSN without invoking a citation template
local p = {}
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ISBN-10 and ISSN validator code calculates checksum across all isbn/issn digits including the check digit. ISBN-13 is checked in check_isbn(). If the number is valid the result will be 0.