Pi, Liang-Wen Max Planck Institute for the Physics of Complex Systems, Max Planck Society;
https://journals.aps.org/pra/abstract/10.1103/PhysRevA.98.043820 (Publisher version)
Vikartofsky, A., Starace, A. F., & Pi, L.-W. (2018). Perturbative representation of ultrashort nonparaxial elegant Laguerre-Gaussian fields. Physical Review A, 98(4): 043820. doi:10.1103/PhysRevA.98.043820.