The DELTA CARD

The Delta punched card is of the Batten‐Cordonnier type which in American publications is called ‘Peek‐a‐Boo’. This card is a simple device for the analysis of the contents of a growing collection of scientific literature covering a special well‐defined area of research. It is recommended in cases where a scientific research worker, or a small group of workers, needs a thorough analysis of the relevant subject from several independent aspects at one time. Further possible applications of this card are the analysis of a collection of research data, the analysis of statistical data, or of material in archives.