4 ms·

Probably because it was top secret.

• xpe 5y ago
  Yes, it was classified. But that isn't the point. You can cite just about anything -- ranging from phone conversations to in-person interviews, from cookbooks to journal articles. Yes, even documents from WikiLeaks or other data dumps. It isn't hard. Citing your sources shows that you are careful and you respect your readers. Make it easier for them follow the trails where they lead. It also saves time, energy, and electrons. Write out the reference once, help N people later.