1. Pontinen, P.: Low Level Laser Therapy as a Medical Treatment Modality. Art Urpo, Ltd., Publishers, 1992, pp 99-101.
2. Trelles, M., and Mayayo, E.: The Growth of Hair under Influence of the He-Ne Laser Beam: Histological Study. Sorrento. World Congress of Laser-Therapy, 1982.
3. Trelles, M., Mayayo, E., Schmidt, C., Igllesias, J., and Barber, J.: Laser Para la Salud y la Estetica. Etecnes, 2nd. edition, 1983, pp 98-107.