"Determination of the optical character of a uniaxial crystal with the gypsum plate. Quartz (+)." -Johannsen,…
"Determination of the optical character of a uniaxial crystal with the gypsum plate when the center…
"Determination of the optical character of a biaxial crystal in a section cut perpendicular to the acute…
"Determination of the optical character of biaxial crystals in sections showing the emergence of an…
"Determination of the optical character of a uniaxial crystal with the mica plate. (a) Positive. (b)…