基数関数
ISBN 90-6196-196-3
↑ Engelking, Ryszard (1989). General Topology. Heldermann Verlag, Berlin. ISBN 3885380064
↑ Monk, J. Donald: Cardinal functions on Boolean algebras. "Lectures in Mathematics ETH Zürich". Birkhäuser Verlag, Basel, 1990. ISBN 3-7643-2495-3.
↑ Monk, J. Donald: Cardinal invariants on Boolean algebras. "Progress in Mathematics", 142. Birkhäuser Verlag, Basel, ISBN 3-7643-5402-X.