1. APA Citation Resources

2. In-text Citation Example
Rutherford's model of the atom is called the planetary model because the electrons are thought to orbit the nucleus like the planets around the sun (History, n.d). According to Rutherford's model most of the mass of the atom was concentrated in the center. (Doud, n.d)
(History, n.d)
Bibliography Example
Contributors' names (Last edited date). Title of resource. Page #. Retrieved from address
Doud, T. (n.d.). The 2,400-year search for the atom - Theresa Doud. Retrieved August 29, 2016, from
History of the Atom (n.d.). Retrieved August 29, 2016, from of-the-Atom-::of::-Atoms-::of::-CK-12-Physical-Science-For-Middle-School/