1. https://www.theguardian.com/science/2014/nov/30/whats-the-secret-to-holding-your-breath
2. https://en.wikipedia.org/wiki/Respiratory_acidosis
3. https://www.news-medical.net/news/20201106/Why-low-oxygen-damages-the-brain.aspx
4. https://www.newyorker.com/tech/annals-of-technology/pushing-the-limits-of-extreme-breath-holding
5. https://www.scientificamerican.com/article/the-limits-of-breath-holding/
6. https://digg.com/2017/what-would-happen-if-you-held-your-br
7. https://en.wikipedia.org/wiki/Cerebral_hypoxia