SuDoc (Superintendent of Documents Classification), the system used to classify national government documents is unlike the other two systems we've looked at in previous lessons. The LC and Dewey systems are organized so that books and journals about the same subject are located together on the shelves. The SuDoc system, however, is organized by the issuing agency or governmental body. Given the scope of information published by the House of Representatives, for example, materials under the House call number will vary greatly. It is often impossible to guess which agency published the information you're looking for, so useof the catalogs is encouraged.