If you use sba in your published work, you should include a reference to the following paper (bibtex entry):
@article{lour09, author="M.I. A. Lourakis and A.A. Argyros", title="{SBA: A Software Package for Generic Sparse Bundle Adjustment}", journal="ACM Trans. Math. Software", volume="36", number="1", year="2009", pages="1-30", publisher="ACM", address="New York, NY, USA", doi="http://doi.acm.org/10.1145/1486525.1486527" }
A local copy of the paper is here.