Sight-saving Class Exchange.

no.12; no.14; no.17; no.26 1929 Jun; no.27 1929 Oct; no.28 1929 Dec; no.29 1930 Jan; no.34 1930 Nov; no.35 1931 Feb; no.36 1931 Mar; no.37 1931 Jun; no.38 1931 Nov; no.39 1932 Feb; no.40 1932 Oct; no.41 1932 Dec; no.42 1933 Feb; no.43 1933 Apr; no.44 1933 Jun; no.45 1933 Oct; no.46 1933 Dec; no.22-50 1928-34; no.47 1934 Feb; no.48 1934 Apr; no.49 1934 Jun; no.50 1934 Nov; no.51 1935 Feb; no.52 1935 Apr; no.53 1935 Jun; no.54 1935 Nov; no.55 1936 Feb; no.57 1936 Jun; no.58 1936 Nov; no.59 1937 Feb; no.60 1937 Apr; no.61 1937 Jun; no.62 1937 Nov; no.63 1938 Feb; no.64 1938 Apr; no.65 1938 Jun; no.66 1938 Nov; no.67 1939 Feb; no.68 1939 Apr; no.69 1939 Jun; no.70 1939 Nov; no.71 1940 Feb; no.72 1940 Apr; no.73 1940 Jun; no.74 1940 Nov; no.75 1941 Feb; no.76 1941 Apr; no.77 1941 Jun; no.78 1941 Nov; no.51-81 1935-42; no.79 1942 Feb; no.80 1942 Apr; no.81 1942 Jun; no.82; no.82 1942 Nov