Toy Building Sets and Building Blocks
US 3,034,254. Application: 2 Mar 1959, Granted: 15 May 1962

Detail, pages 1—2 of 4.

Patent family:

Spielzeugbauelement. AT 238602B. 25 Feb 1965.

Bauspielzeug. CH 371379. 30 Sep 1963.

Bauelement für Bauspielzeug. DE 1076007. 21 Dec 1961.

För Byggleksaker avsett Byggelement. SE 315536. 1 Jul 1968.

Toy Building Element including a Rotatable Bushing. US 3034254. 15 May 1962.

In several countries this patent was part of the claims for the original stud-and-tube coupling:

Improvements relating to Toy Building Sets. GB866557. 24 Apr 1961.