In her Letter to Mary, Jane claimed that she had been poisoned and that as a result her hair had fallen out.
This alleged poisoning is referred to in the following:
Lady Jane Grey: A Tudor Mystery by Eric Ives
Edward VI: Henry VIII’s Overshadowed Son by Stephanie Kline
The Accession Coronation and Marriage of Mary Tudor as related in four manuscripts of the Escorial translated by C V Malfatti
Great Ladies: The Forgotten Witnesses to the Lives of Tudor Queens by Sylvia Soberton
Medical Downfall of the Tudors: Sex, Reproduction & Succession by Sylvia Soberton
The History of Mary I: Queen of England by J M Stone
Crown of Blood: The Deadly Inheritance of Lady Jane Grey by Nicola Tallis
Documents of Lady Jane Grey: Nine Days Queen of England 1553 by James D Taylor Jr
Children of England: Rivals for the Throne by Alison Weir