Yup - The requirements of each clause can be in separate documents and they do not have to reference the clause, either. They don't have to be in the quality manual. But... Most companies have, at the least, a matrix which points to the document(s) which fulfill each applicable clause of the standard so it's very clear each of the clauses is addressed in their quality system. Back in the 1990's it was sort of expected that the quality manual had to address every clause in the standard. These days a quality manual can consist of little more than a high level flow chart.