Turchin, Valentin F. (1989). "Introduction to Refal". REFAL-5 programming guide & reference manual. Holyoke: New England Publishing Co. Archived from the original on 2008-07-03. Retrieved 2010-04-05.
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Turchin, Valentin F. (1989). "Introduction to Refal". REFAL-5 programming guide & reference manual. Holyoke: New England Publishing Co. Archived from the original on 2008-07-03. Retrieved 2010-04-05.