Cano, F. J., Sanduvete, S., Chacón, S., Rodríguez, L., García, J., Antuña, M. A. & Pérez, J. A. (2015). Factor structure of the Spanish version of the Life Orientation Test-Revised (LOT-R): testing several models. International Journal of Clinical and Health Psychology, 15(2). doi:10.1016/j.ijchp.2015.01.003
http://link.springer.com/article/10.1007/s11135–007-9085–3