@article {kountouris2007effectiveness,
	title = {The effectiveness of external cues on learning spiking in volleyball},
	journal = {International journal of performance analysis in sport},
	volume = {7},
	number = {2},
	year = {2007},
	pages = {117{\textendash}125},
	publisher = {University of Wales Institute, Cardiff},
	url = {http://www.ingentaconnect.com/content/uwic/ujpa/2007/00000007/00000002/art00011},
	author = {Kountouris, Panagiotis and Laios, Yannis}
}
