If you want to reference SPHysics, either the code or the User Guide, please follow this format:
In text: Gómez-Gesteira et al. (2009)
In bibliography: Gómez-Gesteira, M., Rogers, B.D., Dalrymple, R.A., Crespo, A.J.C. and Narayanaswamy, M., 2009, User Guide for the SPHysics Code v1.4, http://wiki.manchester.ac.uk/sphysics.
In text: SPHysics
In bibliography: SPHysics code v1.4, http://wiki.manchester.ac.uk/sphysics.
v1.2
The Guide:
In text: Gómez-Gesteira et al. (2008)
In bibliography: Gómez-Gesteira, M., Rogers, B.D., Dalrymple, R.A., Crespo, A.J.C. and Narayanaswamy, M., 2008, User Guide for the SPHysics Code v1.2, http://wiki.manchester.ac.uk/sphysics.
The Code:
In text: SPHysics
In bibliography: SPHysics code v1.2, http://wiki.manchester.ac.uk/sphysics.
v1.0
The Guide:
In text: Gómez-Gesteira et al. (2007)
In bibliography: Gómez-Gesteira, M., Rogers, B.D., Dalrymple, R.A., Crespo, A.J.C. and Narayanaswamy, M., 2007, User Guide for the SPHysics Code v1.0, http://wiki.manchester.ac.uk/sphysics.
The Code:
In text: SPHysics
In bibliography: SPHysics code v1.0, http://wiki.manchester.ac.uk/sphysics.