A selector function is defined as a choice function, which selects one particular argument in a set of arguments according to given selection criteria. A notation has been developed which states the algorithms that apply for symbolic treatment of the selector functions. Some examples of selector functions are given and the corresponding physical interpretations indicated.

It is shown that a simple circle diagram can be developed which will readily convert the dynamic amplitude ratio and phase shift characteristics of analog computing units (or similar electronic devices) into the corresponding rms-error functions. These rms-error functions which directly conform with the static dc accuracy specifications generally used, can be plotted in a new diagram giving the operational error characteristics of the units. By the use of this error diagram the signal frequency bands can be determined which will give satisfactory dynamic operations of the analog computing units within given error limits.

This bibliography, which covers material published through 1958, contains nearly 700 references to articles, books, seminars, and other bibliographies pertaining to the theory of switching circuits and logical algebra. A relatively large number of the references are to foreign works, of which the Russian contribution is by far the greatest. An effort has been made to give exact bibliographical references; wherever possible, the titles of the foreign items have been listed in their original language, together with an English translation. Appended to the chronological bibliography are a list of books, a list of other bibliographies, an author index, a subject index, a list of periodicals, and a list of frequently used Russian abbreviations.