The Sibley-Munroe checklist was a landmark document in the study of birds. It drew on extensive DNA-DNA hybridisation studies to reassess the relationships between modern birds.
... expression to the left of "=", that will make it a perfect square trinomial of the form x2 + 2xy + y2. Since "2xy" in this case is (b/a)x, we must have y = b/(2a), so we ...