Greek letters are frequently used in statistical formulas and notations, in mathematical composition, in certain chemical names for drugs, and in clinical and technical terms (see 14.11, Abbreviations, Clinical, Technical, and Other Common Terms; 14.12, Abbreviations, Units of Measure; 15.0, Nomenclature; 20.0, Study Design and Statistics; and 21.0, Mathematical Composition). The editors of JAMA and the Archives Journals prefer the use of Greek letters rather than spelled-out words, unless usage dictates otherwise. Consult Dorland's and Stedman's medical dictionaries for general terms. These sources may differ in the representation of terms, ie, -fetoprotein (symbol) (Stedman's) and alpha fetoprotein (Dorland's). If the Greek letter, rather than the word, is found in either of these sources for the item in question, use the letter in preference to the word.