Most ready reference sources are of specific frequency i.e. annual, biennial, or published at specific or irregular interval. They are referred to answer factual and trend questions. So, by their nature, they turn out to be outdated soon after the latest editions are published. It is essential thus, to check them for the special criteria.
Recency: As ready reference sources are referred to locate information on dates, events, persons, organisations or specific subject, they should be checked for recency. Some few well-known events, changes in addresses, recruitment of eminent scholars,
important dates, inventions or notable achievements of the previous year are included or not.
Brevity: Since most of these sources are browsed through to enhance general knowledge, the information should be available in brief, pinpointed, factual form which are easy to locate and remember. The long descriptive articles are used for serious study.
Trends in Development: They should indicate trends in development. One should be able to see the continuity in development over the years whether it is scientific advances, political events, sociological research, personalities or organisations.
Methods of Compilation: They are varied types and are different in their nature, scope and coverage. Hence, one has to look for the method used for its compilation. The data may be collected from the primary or secondary source. Sometimes either census or survey method is used for compilation.