The periodicals themselves may or may not be owned by any individual library. Full-text databases may make historical documents available online, such as the U.S. Constitution . Others supply current information, such as periodical articles or daily entries from the Federal Register . Few periodical article databases provide the full-text for every article listed. The primary reason for this is that some periodical publishers are reluctant to relinquish their copyright ownership rights, by allowing their articles to be made available online, for any fee.
Numeric databases supply quantitative data.
A few examples of the data available in numeric databases are company financial information, census statistics and national labor data. The experienced researcher knows that not all pertinent information can be found online. All researchers should resist the temptation to rely solely on that which is conveniently found online. The articles or other information found online may or may not be all that useful. Periodical articles identified but not available in full-text online might be found in the local library.