@article{lejpt28057,
 author={Pierno, A. and Di Noia, L. P. and Rubino, L.},
 year={2016},
 title={Ancillary services provided by PV power plants},
 journal={Leonardo Electron. J. Pract. Technol.},
 volume={15},
 number={28},
 pages={57-76},
 url={http://lejpt.academicdirect.org/A28/057_076.pdf}
}