Symbolab is a semantic web search engine for math and science. It allows users to search for equations, formulas and expressions using mathematical symbols and scientific notations as well as full text search. The stated goal of the site is to provide the most relevant search results that are theoretically and semantically similar, rather than visually.
A personal research assistant. Zotero is the only research tool that automatically senses content, allowing you to add it to your personal library with a single click. Whether you're searching for a preprint on arXiv.org, a journal article from JSTOR, a news story from the New York Times, or a book from your university library catalog, Zotero has you covered with support for thousands of sites.