Per anno

@book{principiamathematica-book1927,
    apice = {PrincipiamathematicaBook1927},
    author = {Whitehead, Alfred North and Russell, Bertrand},
    isbn = {9780521067911},
    month = jan,
    publisher = {Cambridge University Press},
    title = {Principia Mathematica},
    url = {https://www.cambridge.org/it/academic/subjects/mathematics/logic-categories-and-sets/principia-mathematica?format=WX&isbn=9780521067911},
    year = 1927
}