doi.org/10.1088/0950-7671/42/6/307
J. Sci. Instrum.

van Deenen, P. J., Matitti, T.& Vermeer, A. (1965). A transistor amplifier for registration of the low current part of a Langmuir probe characteristic. J. Sci. Instrum., 42.https://doi.org/10.1088/0950-7671/42/6/307