R. Bordoloi, and T. Tamuli, G. D. Baruah. “A Study on Optogalvanic- Like Effect in Discharge and Vector Representation of Transistion- Probability”. Journal of International Academy of Physical Sciences, vol. 8, no. 1-4, Dec. 2004, pp. 99-105, https://www.iaps.org.in/journal/index.php/journaliaps/article/view/787.