It depends what you are using it for.
For simple calibration, and most modelling:
Bronk Ramsey, C.,(2001), Development of the Radiocarbon calibration
program OxCal, Radiocarbon, 43, 355-363, Proceedings of 17th
International 14C Conference
For wiggle matching of tree ring sequences:
Bronk Ramsey, C., van der Plicht, H. & Weninger, B.,(2001), "Wiggle
Matching" Radiocarbon dates, Radiocarbon, 43(2A), 381-389
For deposition models:
Bronk Ramsey, C.,(2008), Deposition models for chronological records,
Quaternary Science reviews, 27, 42-60
I would suggest also giving the OxCal version number and the website:
http://c14.arch.ox.ac.uk/oxcal.html