George Allen & Unwin Ltd. (1994). How things work: The universal encyclopedia of Machines Vol. II. Harper Collins Publications.
Chicago-viite (17. p.)George Allen & Unwin Ltd. How Things Work: The Universal Encyclopedia of Machines Vol. II. New delhi: Harper Collins Publications, 1994.
MLA-viite (9. p.)George Allen & Unwin Ltd. How Things Work: The Universal Encyclopedia of Machines Vol. II. Harper Collins Publications, 1994.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.