The document discusses different types of information sources, dividing them into documentary and non-documentary sources. Documentary sources are further divided into primary, secondary, and tertiary sources. Primary sources include periodicals, conference proceedings, research reports, patents, standards, theses, annual reports, government publications, and unpublished sources. Secondary sources consist of indexes, bibliographies, reviews, textbooks, and reference books. Tertiary sources provide bibliographies of other sources, directories, guides to literature, and lists of research. Non-documentary sources include humans, organizations, mass media, and cyber media.