Continuing from last time, variation 3 is a correct set of attributions. So is variation 1 (the actual book), if X and A had the contract assumed in the hypothetical that made A's commissioned work a work for hire. Variation 2 is a very rare situation: the "professional celebrity" and the "professional author" (who is not a well-known author) agreed to split credit evenly, and convinced the publisher to do so.

   Variations 4 and 5—which are by far the most common situations—are much more troublesome. Variation 4 discloses that "Brand X" is not really 100% "Brand X" only in the copyright attribution; Variation 5 does not disclose it at all. Variation 4 is at least misleading under the FTC Act standard, and Variation 5 is an outright lie. Why? Because both of them fail to disclose in the marketing materials (the cover) or the inside packaging (the title page) that the work advertised as "Brand X" is not.