Thanks, Rose.
The first book of his images, Early Color, is well recommended. He frequently used out of date film to get faded colours which often works surprisingly well. If you like his work, or that of any other published photographer, it is worth buying the books when they are published as they are not always reprinted or there is a long gap between editions. This means that they can then go up in value and I see an optimist on Amazon is asking £350 for a first edition, even though you can still buy it at prices starting at £23 from other sellers!
One good place for photography book reviews is The Online Photographer, which occasionally carries recommendations. If you do buy via the blog, use their UK Amazon link so that the author gets a bit of commission on your purchase. It won't cost any extra and you help to support a worthwhile website.
http://www.amazon.co.uk/Saul-Leiter-Ear ... aul+leiter