1. A plea for more general use of the cross cylinder;Crisp;Trans. Amer. Acad, of Ophth. and Oto-Laryng,1922
2. A suggestion in cross-cylin der technique;Danielson;Amer. Jour. Ophth.,1929
3. Cross cylinders in refraction;Hurst;Texas State Jour. Med.,1926
4. Trial set of small lenses and a modified trial frame;Jackson;Trans. Amer. Ophth. Soc.,1887
5. The crossed cylinder in the determination of the refraction;Schneideman;Ophth. Record,1900