Grudem's critique of the LSJ: 'source' is literal (rivers only), not metaphorical; plural kephale = sources, singular = mouth of river

Wayne Grudem (in his 1990 article) criticizes the LSJ on several points: (1) 'source' in the LSJ is a literal meaning for rivers, not metaphorical, so it cannot apply to Paul's metaphorical usage; (2) the only ancient text that mentions 'source of a river' as kephale uses the plural form for sources but the singular for the mouth of the river — suggesting 'extremity' (already an established meaning) rather than 'source'; (3) the LSJ never applies 'source' to a person being the source of another person.