Altitude and it's Effects

Travel at High Altitude, Medex, ISBN 0-901100-76-5 (free to download from Medex)
Altitude Illness: Prevention & Treatment, The Mountaineers Books, Bezruchka, ISBN 0-89886-685-5 (pocket sized guide)
Medicine for Mountaineering, The Mountaineers Books, Wilkerson et al, ISBN-10: 1594850763, ISBN-13: 978-1594850769

British Mountaineering Council (BMC) website
International Mountaineering and Climbing Federation (UIAA) website

Walking Guides

Sierra Nevada - La Integral de los 3,000, Editorial Piolet, 1:25,000, ISBN 9788493787493
Walking in the Sierra Nevada, Cicerone, Walmsley,  ISBN-10: 1852844353, ISBN-13: 978-1852844356
Walk! The Alpujarras, Discovery Walking Guides, Davis, ISBN 1-904946-23-2
Sierra Nevada - Alpujarras Walking Guide, Discovery Walking Guides Ltd, Brawn, ISBN-10: 1899554378, ISBN-13: 978-1899554379

Maps

Sierra Nevada, La Alpujarra Map and Hiking Guide, 1:40,000 Illustrated Map, ISBN-10: 8480902558, ISBN-13: 978-8480902557
Alpujarras Tour & Trail Map, Discovery Walking Guides, (waterproof) 1:40,000, ISBN 10: 1904946259, ISBN 13: 9781904946250
Sierra Nevada: Alpujarras/Marquesado del Zenete, Editorial Penibetica, 1:40,000, ISBN: 9788493444938
GR 240: Tour of the Sierra Nevada, Editorial Penibetica, 1:40,000,
Sierra Nevada - Las Alpujarras, IGN, 1:100,000,