Heres a few,
http://anzacsteel.hobbyvista.com/Armoured%20Vehicles/centurionph_1.htm
http://encyclopedia.thefreedictionary.com/Centurion%20tank
http://encyclopedia.thefreedictionary.com/Centurion%20tank
http://w1.500.telia.com/~u50015076/
You should also pick up squadron signals Centurion in action book as this has a wealth of photos and facts in it, its about 10.00 USD.