Koekoek, R. (1969). The structure of papain: An X-ray diffraction study at 2.8Å resolution. V.R.B.-Offsetdrukkerij.
Čikaški stil citiranja (17. izdanje)Koekoek, Roelof. The Structure of Papain: An X-ray Diffraction Study at 2.8Å Resolution. Groningen: V.R.B.-Offsetdrukkerij, 1969.
MLA način citiranja (8. izdanje)Koekoek, Roelof. The Structure of Papain: An X-ray Diffraction Study at 2.8Å Resolution. V.R.B.-Offsetdrukkerij, 1969.
Upozorenje: Ovi citati možda nisu uvijek 100% točni.