James R. Choike (1980). "The Pentagram and the Discovery of an Irrational Number". The Two-Year College Mathematics Journal. 11 (5): 312-316. doi:10.2307/3026893. JSTOR3026893. S2CID115390951.
James R. Choike (1980). "The Pentagram and the Discovery of an Irrational Number". The Two-Year College Mathematics Journal. 11 (5): 312-316. doi:10.2307/3026893. JSTOR3026893. S2CID115390951.
James R. Choike (1980). "The Pentagram and the Discovery of an Irrational Number". The Two-Year College Mathematics Journal. 11 (5): 312-316. doi:10.2307/3026893. JSTOR3026893. S2CID115390951.