Best Free Reference

Do you or your patrons suffer from breathing problems or live in areas prone to forest fires or on coasts with temperature inversions? Be sure to check the AQI forecast before venturing outside or taking your next trip. The U.S. Environmental Protection Agency and our National Oceanic and Atmospheric Administration, National Park Service, and many other state and local agencies developed the AirNow system to provide the public with easy access to national air quality information. Type in your zip code to find color-coded maps that rate the air quality in your state or region.

With entries for 9,000 artists and indexing to 2,900 art sites, Artcyclopedia is a search engine guide to great art online. The site is easy to use, with search and browse options. Search by artist’s name, title of a work, or museum. Browse by name, art movement, subject, nationality, medium, or gender. Use the world map to find links to art museums with online exhibits. Artist entries provide extensive links to images of, museums with, and markets for their work. There are links to articles, some of which require the user to log in to view the entire article.

The U.S. Geological Survey (USGS) is responsible for recording and reporting earthquake activity across the United States. It also tracks earthquakes worldwide, locating about 50 such events daily. Use this site to identify the location of the latest earthquakes, their magnitude and intensity, and nearby cities. There is an archive of significant earthquakes. Use the “Top 10” Lists to find statistical data and earthquake information by state or country. Maps are available to download, or you can create probability and hazard maps. The site contains technical information for those who need it and educational material for those seeking more on earthquakes and the hazards they cause. Did you feel the earth move under your feet? Report it to the USGS, and help the agency and other communities learn from your experience!

Developed by the Federal Reserve Bank of St. Louis, FRED includes more than 240,000 economic and financial time series data from dozens of U.S. and international sources. The homepage displays recent research and a glance at the most recent unemployment and ten-year treasury rates, the consumer price index, and the gross domestic product. The site provides tools to help download data, create maps and graphs, and enable users to understand the data better. Short video tutorials explain the tools. Embed FRED in your website by using a customizable widget to display popular data. Download the FRED app for the latest information. Creating an account allows users to develop graphs that will automatically be updated when new data becomes available, save data lists, and build dashboards.

At this site, Princeton University Press brings to the web The Collected Papers of Albert Einstein, a compilation of more than 30,000 documents of the writings and correspondence of Albert Einstein (1879–1955). The site represents 13 volumes from the California Institute of Technology’s Einstein Papers Project, which currently covers from boyhood to 1923. The search box mines the documents in their original language; English-language translations are provided for most items. Using the advanced search offers German and English options. The volumes contain links to the translation, references, indexes, and the archival record from Hebrew University of Jerusalem’s Einstein Archives Online. Additional volumes will be added about every two years following the publication of the relevant print titles.

This site is designed to provide country- and regional-level data using key indicators such as poverty head count, fertility rate, maternal mortality ratio per 100,000 live births, number of weeks of maternity leave, or proportion of seats held by women in national governments. Track change over time and do comparisons by countries within regions. While gender gaps continue to exist in virtually all countries, the data demonstrates that progress is being made, if slowly.

Launched in 2003 to “provide the most accurate and comprehensive nutrition analysis available, and to make it accessible and understandable to all,” Nutrition Data has become one of the most useful nutrition sites on the web. Learn how to read food labels and discover the nutritional effects of freezing, drying, and cooking foods. Search foods by name or nutrient. Compare the nutritional content of foods or find recipes. The tools allow you to find foods based upon needs—for example, generate a list of those that are low carb and low cholesterol, high in protein, low in sodium, high in vitamin A and potassium, etc. Register to create “My ND” and track the nutritional value of the food you eat, create recipes and analyze their nutritional content, and more.

While you can certainly use this site or mobile app to cost out your taxi ride in San Francisco to your hotel from the airport (about $57 including a 20 percent tip, depending on traffic and location), it can tell you so much more. That $57 includes an initial fare of $3.50 plus the metered fare, $44.05, and your tip, $9.51. The trip is 14 miles and will take about 19 minutes. There’s even a suggested route. But wait—for many cities there are other options given through RideGuru. For a trip from London’s Heathrow Airport to the British Museum, for example, a trip of 18.9 miles that takes about 38 minutes (traffic dependent) has an estimated taxi fare is £75.52, but if you have an account with one of the new ride share services such as Uber X, that same trip can cost you only £38.04. RideGuru supports rates from taxis, Uber, Lyft, Sidecar, Hailo, Flywheel, and Curb.

As part of the commemoration of the centennial of the outbreak of World War I, this site collects resources from three major European projects. In collaboration with Oxford University and additional European partners, it’s collecting and digitizing previously unpublished letters, photographs, and other keepsakes. The end of 2013 saw 60,000 items digitized. Second, the site offers a digital collection of 400,000 items from the national libraries of eight countries. Finally, Europeana also includes 650 hours of film on the war. A great place to send students who seek primary materials on World War I; also a valuable genealogical resource.

This new type of weather website offers interactive weather graphs that allow users to pan and zoom through the history of some 4,000 weather stations from around the world. Its aim is to present key pieces of information in an easy-to-read format with hour-by-hour graphs and its unique SparkRadar, which captures the motion of precipitation for the past 12 hours. The designers are James Diebel, who has a PhD in aeronautics and astronautics (Stanford), and Jacob Norda, a software engineer with a master’s in electrical engineering and applied physics (Linkoping Institute of Technology).