Gallardo, Jose Manuel, Giannina Bellone, Rubén Acevedo, and Marcelo Risk. “Ultra-Short-Term Heart Rate Variability Analysis: Comparison Between Poincaré and Frequency Domain Methods”. IEEE Latin America Transactions 20, no. 1 (October 27, 2021): 180–188. Accessed January 28, 2022. https://latamt.ieeer9.org/index.php/transactions/article/view/5433.