https://arxiv.org/abs/gr-qc/9310036
[gr-qc/9310036] A Step Toward Pregeometry I.: Ponzano-Regge Spin Networks and the Origin of...
Abstract page for arXiv paper gr-qc/9310036: A Step Toward Pregeometry I.: Ponzano-Regge Spin Networks and the Origin of Spacetime Structure in Four Dimensions