Two card files were kept in the Malaria Experiment Station: a yellow card file and a red card file. The yellow card file was alphabetically ordered by the last names of the test subjects, while the red card file was ordered by test groups. Every test subject had a card in each card file. At the ITS, the cards were microfilmed in black and white. To record the color of the original card, ITS employees stamped each copy with the respective note. The collection in the Arolsen Archives is now ordered alphabetically and not separated by yellow or red card file.