Williamson, T. (2010). The origins of Hertfordshire. Hertfordshire Publications.
Chicago-čujuhus (17. p.)Williamson, Tom. The Origins of Hertfordshire. Hatfield, Hertfordshire: Hertfordshire Publications, 2010.
MLA-čujuhus (9. p.)Williamson, Tom. The Origins of Hertfordshire. Hertfordshire Publications, 2010.
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