Nagraj Gollapudi on how the yo-yo test became a selection standard for international teams
Frontiers | The Yo-Yo Intermittent Tests: A Systematic Review and Structured Compendium of Test Results | Physiology
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