ଉଇକିପିଡ଼ିଆ:Offline sources
 | This is an essay. It contains the advice or opinions of one or more Wikipedia contributors. This page is not an encyclopedia article, nor is it one of Wikipedia's policies or guidelines, as it has not been thoroughly vetted by the community. Some essays represent widespread norms; others only represent minority viewpoints. |
 | This page in a nutshell: Offline sources are just as valid as online sources. |
Wikipedia's reliable sources guideline states that articles should be sourced with reliable, third-party, published sources. Even though Wikipedia is an online encyclopedia, there is no distinction between using online versus offline sources. In fact, many great sources are only available offline. Don't let that fact scare you away from using them as a source in Wikipedia.
Books are a typical example of an offline source. These are often great resources, with information that can't be found online. Several ongoing projects, such as Project Gutenberg and Google Book Search, aim at digitizing certain books and presenting them online. Even if the books are online, it might be necessary to consult a print edition to double-check any errors from the OCR scanning. Many academic journals only make short abstracts available online. Other content providers, like the Wall Street Journal, publish their content behind a paywall that prevents non-subscribers from accessing the content. Other websites, like the Philadelphia Inquirer, only publish their content online for a few weeks. Sometimes a source was once online, but now is offline (link rot).
That Wikipedia relies extensively on online sources is not surprising, considering the relative ease of accessing such materials. There is also an additional advantage of using online sources, because it allows all users to evaluate the source and its value to the article. However, this reliance on online sources can lead to recentism, where most articles and content are from the internet era.
Special care should be taken when using offline sources. Make sure to provide full bibliographic information, often by using a fully-filled out citation template, like {{cite book}} or {{cite news}}. Complete information helps Wikipedia's readers find the source when they need it, and also increases the source's credibility among the Wikipedia editing community (who may otherwise be skeptical of its reliability). Second, use the quote= parameter within those citation templates to provide some context for the reference. This is especially important when using the off-line source to support a fact that might be controversial or is likely to be challenged.
Sometimes, the use of an offline source will be challenged. Be sure to assume good faith for the user who cited the offline source. They might even be able to provide you a scan or an excerpt from that source. Consider visiting your local library to obtain a copy. Even if the library doesn't have that particular book or journal article, it might be available through interlibrary loan. Also consider posting an inquiry on the relevant WikiProject, because some interested editors might have a copy of that source. The volunteers at WikiProject Resource Exchange might be able to help you coordinate your search.