I am attaching few more links of papers regarding the units.
http://www.physics.utoronto.ca/~phy225h/experiments/thermal-noise/Thermal-Noise.pdf
http://rfic.eecs.berkeley.edu/~niknejad/ee142_fa05lects/pdf/lect11.pdf
http://www.fis.unipr.it/~gigi/dida/strumentazione/harvard_noise.pdf