@article{PismaZhETF.50.458,
    title = {Energy gap in $YBa_2Cu_3O_x$ determined from the data on tunnel experiments with single crystals},
    author = {Al'tfeder, I. B. and Volodin, A. P. and Makarenko, I. N. and Stishov, S. M. and Shubnikov, A. V.},
    journal = {πΙΣΨΝΑ Χ φότζ},
    volume = {50},
    issue = {11},
    pages = {458},
    year = {1989},
    doi = {},
    url = {http://jetpletters.ru/ps/0/article_17158.shtml},
}