Normative Yo-Yo Intermittent Recovery Level 1 and Yo-Yo Intermittent Endurance Level 1 test values of boys aged 9–16 years - ScienceDirect
Assistant Referee Intermittent Endurance Test (ARIET)
Normative Yo-Yo Intermittent Recovery Level 1 and Yo-Yo Intermittent Endurance Level 1 test values of boys aged 9–16years - Journal of Science and Medicine in Sport
HexEndure - Intermittent Endurance Testing
Dynamic Yo Yo test for football refeerees - Dutch Referee Blog