These stories were not issued in their "canonical" order. Numbering has been created from dates of issue. When several titles were issued on the same date, they were numbered according to canonical order within that batch. This series should not be confused with a later hardbound series from the same publisher, also called The Adventures of Tintin. Books were originally issued between 1974 and 2007, and many have been in print ever since, so there are minor variants in circulation. Early numbers originally appeared without barcodes or ISBNs, while all issues now have both. Other points of variance include: prices; brands; indicia; content of barcodes and ISBNs; front matter; and back-cover promos.