Johnson, D., Allender, D., deHoff, R., Maze, C., Oppenheim, E., & Reynolds, R. (1977). Nematic-Smectic-A-Smectic-C Polycritical Point - Experimental-Evidence and a Landau Theory. Physical Review B. https://doi.org/10.1103/PhysRevB.16.470
Johnson, David, David Allender, Richard deHoff, Craig Maze, Everett Oppenheim, and Reese Reynolds. 1977. “Nematic-Smectic-A-Smectic-C Polycritical Point - Experimental-Evidence and a Landau Theory”. Physical Review B. https://doi.org/10.1103/PhysRevB.16.470.
Johnson, D., D. Allender, R. deHoff, C. Maze, E. Oppenheim, and R. Reynolds. Nematic-Smectic-A-Smectic-C Polycritical Point - Experimental-Evidence and a Landau Theory. Physical Review B, 15 June 1977, doi:10.1103/PhysRevB.16.470.