2).

II. A. S. Besicovitch and G. Walker, On the density of irregular linearly measurable sets of points. Proc. of London Math. Soc. (L. M. S.)

**32** (1931), pp. 142–153. III. J. Gillis, On linearly measurable plane sets of points of upper density 1/2. Fund. Math.

**22**, pp. 57–70. IV. J. Gillis, Note on the projection of irregular linearly measurable plane sets of points. Fund. Math.

**26**, pp. 229–233. V. J. Gillis, A Theorem on irregular linearly measurable sets of points. Journal of L. M. S. 10, pp. 234–240. VI. G. W. Morgan, The density directions of irregular linearly measurable plane sets. Proc. of L. M. S.

**38** (1935), pp. 481–494. We shall refer the cited papers by the Roman figures standing in front of them.

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