R. G. Latham, A Handbook of the English Language
“ The -n is by no means radical; besides which, it is the sign of an accusative case, and is not the sign of a nominative.§ 213. Dative.—In the antiquated word whilom (at times) , we have a remnant of the old dative in -m. The sense of the word is abverbial; its form, however, is that of a dative case.§ 214. Genitive.—Some call this the possessive case. It is found in substantives and pronouns (father's, his) , but not in adjectives. It is formed like the nominative plural, by the addition of the lene sibilant (father, fathers; buck, bucks) ”
