1. Laser Beams and Resonators
2. D. R. Hall, P. E. Jackson, and M. W. Sasnett, Physics and Technology of Laser Resonators (Taylor & Francis Group, New York, 1989), pp. 132–142.
3. A. E. Siegman, OSA Trends in Optics and Photonics Series (OSA, Washington, DC, 1998), Vol. 17, p. 184.
4. Beam propagation and the ABCD ray matrices
5. Beam propagation (M^2) measurement made as easy as it gets: the four-cuts method