@misc{changes+in+sludge+quality+at+the+water+treatment+plants,
    author = {Balcerzak, Wojciech i Rybicki, Stanisław M.},
    title = {Changes in sludge quality at the water treatment plants},
    journal = {Technical Transactions},
    address = {Kraków},
    publisher = {<a href=\"http://www.wydawnictwo.pk.edu.pl/\" target=\"_blank\">Wydawnictwo PK</a>},
    date = {2014},
    number = {Y. 111, iss. 1-Ś}
}