1999, Matt Ridley, Genome, Harper Perennial 2004, p. 167:Dopamine and norepinephrine are so-called monoamines.
2001, Leslie Iversen, Drugs: A Very Short Introduction, Oxford 2001, p. 55:The first effective drugs used to treat clinical depression were compounds that act by enhancing the activity of chemicals known as monoamines in the brain.