A helpful rules lawyer is usually not a problem. Although this guy seems to be more disruptive than helpful, I think ther are a few things yuo can do to limit his disruptions.
You say it slows the game down when he turns to the books to find a rule. I guess this means that it is his turn when he does this, thus everyone is waiting on him.
What we do in my group is, the DM never looks up rules while the game is going on. He has too much to deal with and he is involved with all the players at the same time. If he stops to look up a rule, the whole game stops. By contrast, the players are not always doing something. Often times, the players are sitting there waiting for their turn. So, we deligate responsability. If there is a rule question, whoever is not DMing, and not about to have a turn, is elected to look up the rule. This keeps the game going.
Also, if the player knows (suspects) there will be a rules question when his turn comes up, he should look up that rule BEFORE his turn happens, so when it is his turn he can take x action and if the DM questions it he already has the book open to the page.
If he doesn't do this, you might consider putting a time limit on how long players have to announce their actions each turn. That will help him realize that he needs to be ready when it is his turn.
And you (the DM) should take the time to read up on any vague rules that might crop up before the game session even starts. It is annoying to have your rulings questioned, but like other people here have mentioned, everyone at the table needs to be playing with the same set of rules or there will be misunderstandings and confusion.
Finally, I think your real problem is just the newness of your group. Give it a few more weeks, or even a couple months and you will notice that your group willl be begin to operate more smoothly.
You say it slows the game down when he turns to the books to find a rule. I guess this means that it is his turn when he does this, thus everyone is waiting on him.
What we do in my group is, the DM never looks up rules while the game is going on. He has too much to deal with and he is involved with all the players at the same time. If he stops to look up a rule, the whole game stops. By contrast, the players are not always doing something. Often times, the players are sitting there waiting for their turn. So, we deligate responsability. If there is a rule question, whoever is not DMing, and not about to have a turn, is elected to look up the rule. This keeps the game going.
Also, if the player knows (suspects) there will be a rules question when his turn comes up, he should look up that rule BEFORE his turn happens, so when it is his turn he can take x action and if the DM questions it he already has the book open to the page.
If he doesn't do this, you might consider putting a time limit on how long players have to announce their actions each turn. That will help him realize that he needs to be ready when it is his turn.
And you (the DM) should take the time to read up on any vague rules that might crop up before the game session even starts. It is annoying to have your rulings questioned, but like other people here have mentioned, everyone at the table needs to be playing with the same set of rules or there will be misunderstandings and confusion.
Finally, I think your real problem is just the newness of your group. Give it a few more weeks, or even a couple months and you will notice that your group willl be begin to operate more smoothly.