*Caral quipu*Transcript of BBC Horizon program about Caral*"The mother of all civilisations", "The Times of India", 16 Dec 2007, retrieved 2007-12-19.
* Caral quipu* Transcript of BBC Horizon program about Caral* "The mother of all civilisations", "The Times of India", 16 Dec 2007, retrieved 2007-12-19.