Elegantiarum Linguae Latinae Libri Sex

Suus does not lack a nominative. Ch. XIII.
That it is permitted to speak not only by means of the nominative, as in “His son sees him,” but also by means of other cases. Ch. XIV.
Certain remnants of the rules, regarding when we use these pronouns indifferently and when differently. Ch. XV.
How sui and suus are resolved in construction into is, ipse, and ille. Ch. XVI.