References

1. "Machines." Janice Van Cleave, John Wiley, and Sons, New York. ISBN: 0-471-57108-3
2. "Bathtubs, Slides and Roller Coaster Rails: Simple Machines That Are Really Inclined Planes." Christopher Lampton, Millbrook Press, 1991. ISBN: 1-878841-23-8
3. "Making Science Work: Forces and Machines." Terry Jennings, Raintree Steck-Vaughn Company, Austin, 1996. ISBN: 0-8172-3961-8
4. "Simple Machines Made Simple." Ralph St. Andre, Teachers Ideas Press, 1993. ISBN: 1-56308-104-7
5. "Starting with Science: Simple Machines." Deborah Hodge, Kids Can Press, Buffalo, 1998. ISBN: 1-55074-399-6
6. "Investigate and Discover Forces and Machines." Robert Gardner, Julian Messner Press, Englewood Cliffs, 1991. ISBN: 0-671-69046-9
7. "Science Factory: Work and Simple Machines." Jon Richards, Cooper Beech Books, Brookfield, 2000. ISBN: 0-7613-1159-9
8. "Pulley Activities." NES Arnold, World Class Learning Materials, Baltimore. ISBN: 1-884461-08-5
9. "Marbles, Roller Skates and Doorknobs: Simple Machines That Really Work." Christopher Lampton, Millbrook Press, 1991. ISBN: 1-878841-24-6
10. Unknown.