The second command is the one that actually specifies the .bib file you wish to use. The ones I created for this tutorial were called , , . ., , but once again, you don't include the file extension. At the moment, the .bib file is in the same directory as the LaTeX document too. However, if your .bib file was elsewhere (which makes sense if you intend to maintain a centralized database of references for all your research), you need to specify the path as well, \bibliography{/some/where/sample} or \bibliography{../sample1} (if the .bib file is in the parent directory of the .tex document that calls it).

The formula is printed in a way a person would write by hand, or typeset the equation. In a document, entering * mathematics mode * is done by starting with a $ symbol, then entering a formula in TeX syntax, and closing again with another of the same symbol. Knuth explained in jest that he chose the dollar sign to indicate the beginning and end of mathematical mode in plain TeX because typesetting mathematics was traditionally supposed to be expensive. [17] * Display mathematics* (mathematics presented centered on a new line) is similar but uses $$ instead of a single $ symbol. For example, the above with the quadratic formula in display math: