Machu Picchu's Sacred Sisters; Choquequirao and Llactapata. G Ziegler and JM Malville. (Johnson Publishing, Boulder 2014.

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1) Lost City of the Incas: The Story of Machu Picchu and its Builders. Hiram Bingham, (Atheneum,1972).
2) The Incas and their Ancestors. Michael Moseley, (Thames and Hudson,1992)
3) The Conquest of Peru. William H. Prescott, (New American Library, 1961)
4) The Conquest of the Incas. John Hemming, (Harcourt Brace, 1970)
5) Exploring Cuzco, Peter Frost. (Lima,1984).
6) Machu Picchu-The Sacred Center, Johan Reinhard, (Lima, 1991).
Machu Picchu Abandoned, Gary Ziegler 1996 (self)
9) Puncuyoc, Sacred Inca Sanctuary. Gary Ziegler, (Crestone Press, 1999)
10) Beyond Machu Picchu: Explorations and Adventure in Peru's Remote Vilcabamba, Gary Ziegler, (Creststone Press, 2001)
11) Forgotten Vilcabamba: Final Stronghold of the Inca. Vincent Lee, (Empire publishing, 2000)
12) The White Rock: An Exploration of the Inca Heartland. Hugh Thomson, (Orion Publishing, London, 2001)
13) Realm of the Incas. Max Milligan, (London 2001)
14) Machu Picchu: A Civil Enginering Marvel. Kenneth Wright and Alfredo Valencia Zegarra (ASCE Press, Virginia 2000)
15) The Last Days of the Inca. Kim MacQuarrie, Simon & Schuster, New York, 2007.

16)The Machu Picchu Guidebook. Ruth Wright and Alfredo Valencia Zegarra (Johnson Publishing, Boulder 2001)