Why has the 1930s Dalek invasion of Manhattan never been documented by historians?

I saw a documentary on TV about it a while back, it was called something like "Doctor Who", it was pretty good. I think that it was a reconstruction of the event, with David Tennant and Freema Agyeman starring as leaders of whatever the resistance was called.

But what has been pondering my mind ever since is why this has never been mentioned in any History book, or even Wikipedia?