Classification of systems, [17]

Component, [8], [10], [12]

——, systems of one, [21], [55]

Components, choice of, [12], [13], [14], [76], [313]

——, determination of number of, [13]

——, systems of four, [312]

——, —— of three, [234]

——, —— of two, [76], [207]

——, variation in number of, [11], [14]

Composition, determination of, without analysis, [228], [302]