If your choices are the following:
1. "Noon." The Oxford English Dictionary. Web. 2012. 2nd ed.
2. Noon. The Oxford English Dictionary. 2nd ed. Print. 2012.
3. Noon. The Oxford English Dictionary. 2nd ed. Web. 2012.
4. "Noon." The Oxford English Dictionary. 2nd ed. 1989. Print.
Then the answer is number 4.
