Books can be helpful in terms of a broad/general understanding of the process -- for example, how the SA application process and nomination process work and are related, rough guidelines in terms of timeframes, generally the attributes SAs are seeking, etc.
However, I also urge caution. Each SA is somewhat different in terms of what is requested, how those elements are evaluated/weighted, when and how notifications are made, and even to some extent, what each SA is looking for in an applicant, so there's no "one size fits all." More importantly, the above can change over time -- which is why SA liaison officers must attend training at least every 5 years (for USNA and assume is similar for other SAs). Deadlines also can change, though that's less frequent on the SA side.
The situation with MOCs obviously changes each time there is a change in the person holding the office. And the same MOC has been known to change deadlines from year to year, change whether he/she conducts interviews when and with whom, and what needs to be submitted.
Each SA has a website dedicated to admissions. It is designed for those with no/very limited knowledge of the process. Always start with that, as it's the official source. Each SA has trained liaison officers who are there to answer questions from candidates. And, finally, each SA has Admissions officers, who are the ultimate source of information.
So, read the books for background and then, with that in hand, go to the websites for the SA(s) of choice.