found: Richardson, J. Xmas in Las Vegas, c1966.
found: Bradshaw, C. X-mas at the Johnson's, c2000.
found: Wikipedia, Aug. 2, 2006("Xmas" and "X-mas" are common abbreviations of the word "Christmas." They are sometimes pronounced "eksmas," but they, and variants such as "Xtemass," originated as handwriting abbreviations for the pronunciation "Christmas." This abbreviation is widely but not universally accepted; some view it as demeaning to Christ, whilst others find it helpful to use in text messages and emails and quickly handwritten notes to save space)
found: Griffiths, E. Why get cross about Xmas?, 2004, via BBC News WWW site, Aug. 2, 2006(Far from being an irreligious abbreviation, it appears to have impeccably Christian credentials. The "X" is thought to represent the Greek letter "Chi" - the first letter of the Greek word for Christ, Christos; Before Xmas, there was XPmas, according to Inge Milfull, assistant editor of etymology at Oxford English Dictionaries (OED). She found references in the Anglo Saxon Chronicle as far back as 1021 and says the P was probably dropped later)