Where to look for facts and formulas depends on the subject area and the type of fact for which you're looking. Encyclopedias and handbooks are usually good places to look. An encyclopedia provides a short description of concepts within a subject area. Handbooks take a subject area and condense the known knowledge down into a single volume of summaries, facts, and data (and if appropriate for the subject, formulas, too). Sometimes searching the full text of books and journal articles also can be helpful. And don't forget credible sites on the web, too.
Here's some suggestions ...
Library One Search
Covers many encyclopedias on science and engineering topics. Encyclopedias are usually a good place to look for answers to questions such as what are the longest/shortest, best/worst, first/last of something. Encyclopedia articles frequently list important milestones within a subject area or topic.
To find encyclopedia articles and other types of reference works, such as handbooks, enter your topic in the search box. When you get the results list, look in the left-hand column for the "Content Type" section and check the "Reference" option - this will limit the results to the type of books that contain "facts". You might want to do a separate search in which you select "Book Chapter" as a "Content Type" - although this strategy doesn't always work, when it does work, it will retrieve items you might not fnd otherwise.
Contains the full text of over 5000 science and engineering handbooks, encyclopedias, and databases. Knovel works well when looking for formulas or property data (density, boiling point, elasticity, toxicity, etc.) for substances (chemicals or engineering materials). You can search the whole database at once or search just one of the 5000 books.
These are just a few examples of the types of books in the Knovel database:
A very useful free web site in which you can find an extensive range of mathematical terminology defined. Many (but unfortunately, not all) of the entries in this encyclopedic work are well illustrated and contain a list of references for further reading. This site is a great place to find mathematical formulas and descriptions of mathematical terminology.