Examples of textbooks that use $\overline{\overline{A}}$ to denote set cardinality? I was recently introduced to the notation $\overline{\overline{A}}$ to refer to the cardinality of a set $A$. (The dashes above the set of interest might be more closely spaced together.)
In the hundreds of books I have, I don't have a single textbook that uses this notation to refer to the cardinality of a set. What are some examples of books that do? (I'd be especially interested in one that covers measure theory, but this isn't necessary.)
As mentioned in the comments, Wikipedia also cites this notation as an example.
 A: I looked through some of the books I have where I thought it might be used and found it in the following books. The years given are for the edition in front of me, and the page numbers given are where I think it first appears in the book, which may not be where you’ll see it most used in the book.
Axiomatic Set Theory by Patrick Suppes (1960, p. 109)
Cardinal and Ordinal Numbers by Wacław Sierpiński (1965, p. 136)
Set Theory by K. Kuratowski and A. Mostowski (1968, p. 174)
The Theory of Sets and Transfinite Arithmetic by Alexander Abian (1965, p. 361)
Introduction to Set Theory and Topology by Kazimierz Kuratowski (1962, p. 61)
Abstract Set Theory by Abraham A. Fraenkel (1961, p. 60)
The Theory of Sets and Transfinite Numbers by B. Rotman and G. T. Kneebone (1966, p. 99)
Abstract Set Theory by Thoralf A. Skolem (1962, p.3)
Introduction to Axiomatic Set Theory by Jean-Louis Krivine (1971, p. 23)
Introduction to the Foundations of Mathematics by Raymond L. Wilder (1965, p. 104)
Introduction to Metamathematics by Stephen Cole Kleene (1952, p. 9)
Introduction to Mathematical Logic by Elliott Mendelson (1979, p. 2)
The Mathematics of Metamathematics by Helena Rasiowa and Roman Sikorski (1963, p. 12)
Sets, Lattices, and Boolean Algebras by James C. Abbott (1969, p. 65)
Boolean Rings by Alexander Abian (1976, p. 9)
Real and Abstract Analysis by Edwin Hewitt and Karl Stromberg (1969, p. 19)
Theory of Functions of a Real Variable (Volume I) by I. P. Natanson (1961, p. 27)
The Theory of Functions of Real Variables by Lawrence M. Graves (1956, p. 308)
The Theory of Functions of a Real Variable and the Theory of Fourier’s Series (Volume I) by E. W. Hobson (1927, p. 203)
