Your sources must be from websites or books that are written and maintained by professionals in the field of research. Many websites are not always good science sources because they may not be maintained by people who are fully qualified in that field.
Sources you can safely use are those by the government (ending in .gov), those by universities (ending in .edu), and those by science organizations.
Government organizations might be like: National Institute of Health (nih.gov), US Dept of Agriculture (usda.gov), Dept of Energy (energy.gov);
Universities might look like: MIT (mit.edu); Univ. of Calif. (ucla.edu), Harvard (harvard.edu);
Science organizations like: American Institute of Physics (aip.org); American Chemical Society (acs.org); American Institute of Biological Sciences (aibs.org)
Check out the following websites for information on how to do citations for the "in-paper" citations and the bibliography/citation page.
These are resource pages to keep track of your citation information