Information has three levels, primary, secondary and tertiary.
Primary information is the original research information that comes straight from the researcher.
It can be found in journal articles, conference proceedings, and research reports. It is the most authoritative, since it comes directly from the person doing the research, and the most timely, since it is the initial way in which research results are presented. The lag time between the research being completed and the information being published is usually less than 2 years. Secondary information is compiled information. It has been gathered from various sources and summarized into books and monographic series.