@inbook{400148,
     title = {Vorrede},
     booktitle = {Bernard Bolzano's Schriften},
     series = {GDML\_Books},
     publisher = {Kr\'alovsk\'a \v cesk\'a spole\v cnost nauk v Praze},
     address = {Praha},
     year = {1930},
     pages = {VII-XVI},
     url = {http://dml.mathdoc.fr/item/400148}
}