To cite Somoclu in publications, please use:

Peter Wittek, Shi Chao Gao, Ik Soo Lim, Li Zhao (2015). Somoclu: An Efficient Parallel Library for Self-Organizing Maps. arXiv:1305.1422.

A BibTeX entry for LaTeX users is

@Article{wittek2015somoclu,
  author =    {Wittek, Peter and Gao, Shi Chao and Lim, Ik Soo and Zhao, Li},
  title =     {Somoclu: An Efficient Parallel Library for Self-Organizing Maps},
  journal =   {arXiv:1305.1422},
  year =      {2015}
}

You may also consider adding a link to the code. Please cite the PyPI version:

https://pypi.python.org/pypi/somoclu/

This ensures that Depsy (http://depsy.org/) can aggregate the usage statistics of the library.
