@article{IUPAC+ET07369+2019,
url = {https://doi.org/10.1351/goldbook.ET07369},
institution = {International Union of Pure and Applied Chemistry (IUPAC)},
year = {2019},
title = {El-Sayed rules},
doi = {doi:10.1351/goldbook.ET07369},
edition = {3.0.1}
}