1. Zone Melting;Pfann,1958
2. W.G. Pfann, US Patent 2770761,1957.
3. W.G. Pfann, US Patent 2813048,1957.
4. T.R. Anthony, H.E. Cline, US Patents 3895967, 3898106, 3899361, 3899362, 3901736, 3902925, 3904442, 3910801, 3936319, 3956023, 3956024, 3956026, 3972741, 3972742, 3975213, 3977910, 3979230, 3979820, 3982268, 3982270, 3988757, 3988760, 3988762, 3988764, 3988766, 3988767, 3988768, 3988769, 3988770, 3990093, 3998653, 3998661, 3998662, 4006040, 4010534, 4011582.