Joji Takahashi Partition Properties of M-Ultrafilters and Ideals. 897-907 1987 52 J. Symb. Log. 4 db/journals/jsyml/jsyml52.html#Takahashi87 https://doi.org/10.2307/2273824 http://projecteuclid.org/euclid.jsl/1183742499