In this Q&A, we have assumed Book B is a copyright protected work. To prove infringement, the rights holder in Book B must show that there is: • a causal link between the two works so that the copyright work (Book B), or a substantial part of it, is the source of the infringing work, and • objective similarity between the infringing work (Book A) and the copyright work Effectively, for infringement to occur the copyright work must be copied, however: • the causal link can be made subconsciously, for example where a familiar song is stored subconsciously and parts reproduced