context: He demonstrated that the emission is mostly concentrated in the microwave spectral range.
source: By 1950, Prokhorov was assistant chief of the oscillation laboratory.
reference_original: بحلول 1950، كان Prokhorov مساعداً لرئيس معمل التذبذب.
reference_flipped: بحلول 1950، كانت Prokhorov مساعدة لرئيس معمل التذبذب.