Dictionary of Spoken Russian/Russian-English/Section 13

§13. SPECIAL ADJECTIVES

Adjectives whose stem ends in consonant plus [y] have noun-like forms in the nominatives and in the F accusative, and lack sh forms. In the Mn the inserted vowel is written и: stem [trjetjy-] "third": n третий, третья, третье, третьи, Fa третью. The other forms are regular: Mg третьего, Fgdil третьей, Pgl третьих, and so on. Most of these mean "obtained from" a living being: рыбий "of fish," божий "of God, divine."

Family names and place names whose stem ends in [-in, -ov] have noun-like forms in the nominatives, the F accusative, and the M and Ng, d, and l; thus, the family name Петров has Fn Петрова, a Петрову; Pn Петровы "the Petrov's"; Mg Петрова, d Петрову, l Петрове; the remaining forms are regular, as, Mi я говорил с гражданином Петровым "I was talking with Citizen Petrov."