The Invisible SpectrumJuliet Kaufmann · The Iowa Review · 1998

The invisible solar and lunar spectrumLangley, S. P. · American Journal of Science · 1888

LIX. <i>The invisible solar and lunar spectrum</i>Langley, S.P. · Philosophical Magazine Series 5 · 1888

On the speed of the invisible portions of the spectrumPaul R. Heyl · 1907

Seeing an Invisible Axion in the Supersymmetric Particle SpectrumConlon, Joseph P. · Physical Review Letters · 2006

Experimental determination of wavelengths in the invisible prismatic spectrumLangley, S. P. · American Journal of Science · 1884

Fetal alcohol spectrum disorder: counting the invisible - mission impossible?Chudley, A. E · Archives of Disease in Childhood · 2008