1
Published: 1935
Superior document: Bell telephone system B-848
2
Published: 1933
Superior document: Bell telephone system B-770
3
Published: 1934
Superior document: Bell telephone system B-805
4
Published: 1935
Superior document: Bell telephone system B-890
5
Published: 1936
Superior document: Bell telephone system B-960
6
Published: 1931
Superior document: Bell telephone system B-640
7
Published: 1934
Superior document: Bell telephone system B-838