This is a Bookland ISBN code, which means it's an ISBN number encoded as an EAN/UCC-13. You can tell this by the first three digits of the EAN/UCC-13 (978). The numbers after that are the ISBN. You'll notice the last digits differ, though -- EAN/UCC-13 and ISBN calculate their check digits differently (in fact, the check 'digit' on an ISBN can be a digit or the letter X).

EAN/UCC-13
ISBN		1-55728-253-6