Zawadzki, R. F. (1962). Hayes practical science lessons and experiments: Elementary book 4. Hayes School Publishing.
Cita Chicago (17th ed.)Zawadzki, Robert F. Hayes Practical Science Lessons and Experiments: Elementary Book 4. Wilkingburg, PA: Hayes School Publishing, 1962.
Cita MLA (9th ed.)Zawadzki, Robert F. Hayes Practical Science Lessons and Experiments: Elementary Book 4. Hayes School Publishing, 1962.
Atenció: Aquestes cites poden no estar 100% correctes.