Complex sentence: In 1999, he published "Simulation for the social scientist" with Klaus Troitzsch, the first "how to" text book on agent-based simulation, which is now in its second edition.
Split into simpler sentences: In 1999, Nigel, with Klaus Troitzsch, published "Simulation for the social scientist". This was the first "how to" text book on agent-based simulation, and is now in its second edition.