NELSON,THOMAS R.; LUK,TING S.; BERNSTEIN,AARON C. & CAMERON,STEWART M. Laser Filamentation of a Femtosecond Pulse in Air at 400nm, article, October 27, 2000; (https://digital.library.unt.edu/ark:/67531/metadc723089/m1/1/: accessed April 25, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .