 He was competent not only in English philology, but also in Scandinavian and Celtic, making him ideally qualified as an authority on linguistic aspects of the place-names of England.His other work on English included scholarly editions of classic early-modern works such as John Jones' "Practical Phonography" of 1701 (1907), the anonymous "Writing Scholar's Companion" of 1695 (1911), John Lydgate's "Siege of Thebes" (1930).Notable other books or booklets were that on modern English phonology and morphology originally published in German in 1914 and still being reprinted in 1965 (English edition finally after Ekwall's death, in 1975); and that on the genitive of groups, with much relevance for place-name studies (1943).