European green woodpecker to split this species into three distinct species: "P. viridis" (Linnaeus, 1758) and "P. innominatus" (Sarudny & Loudon, 1905). The Iberian green woodpecker, ("P. sharpei"), has been split by some taxonomists including the IOC. More than 75% of the range of the European green woodpecker is in Europe, where it is absent from some northern and eastern parts and from Ireland, Greenland and the Macaronesian Islands, but otherwise distributed widely. Over half of the European population is thought to be in France, Spain and Germany, with substantial numbers also in Portugal, the United Kingdom, Sweden, Russia, Croatia, Romania and Bulgaria.
An Essay on the Nature and Significance of Economic Science on economic methodology in generating a range of tightly-argued, radical implications from a simple definition, for example in admitting an "aspect" of behaviour (rather than a list of behaviours) but not limiting the subject-matter of economics, provided that the influence of scarcity impinges on these (pp. 16–17). The broad behavioural definition is credited for its consistency with the expanding boundaries of economics decades later. In this Robbins both narrows the definition of economics, thereby demonstrating the usefulness of deduction, and opens up the subject-matter of economics. Robbins's "Essay" is one of the most-cited works on the methodology and philosophy of