@article{PismaZhETF.10.161,
    title = {Investigation of'Light Spark and of Other Optical Effects in Focusing of Light by a Lens with a Channel on the Axis},
    author = {Askar'yan, G. A. and Savchenko, M. M. and Stepanov, V. K.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {10},
    issue = {4},
    pages = {161},
    year = {1969},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_25707.shtml},
}