@misc{an+improved+mathematical+proof+for+zero+stiffness+postbuckling,
    author = {Höfinger, Gerhard i Mang, Herbert A.},
    title = {An improved mathematical proof for „zero-stiffness” postbuckling},
    journal = {Czasopismo Techniczne. Mechanika},
    address = {Kraków},
    publisher = {<a href=\"http://www.wydawnictwo.pk.edu.pl/\" target=\"_blank\">Wydawnictwo PK</a>},
    date = {2010},
    number = {R. 107, Z. 20, 4-M}
}