McKnown, Robin
The fabulous isotopes
Holiday House, 1962
 Buku Teks
Coppard, AE
Silver circus
[T.t.] [t.p.] [t.th.]
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Foskett, A. C.
The subject approach to information / A.C. Foskett
Library Association Publishing, 1996
 Buku Referensi
Walker, Jearl, 1945-
The flying circus of physics
John Wiley & Sons, 1977
 Buku Teks
Vaessens, Thomas
Circus Dubio & Schroom
De Arbeiderspers , 1998
 Buku Teks