[FOM] Order-type of nonstandard models

[Ali Enayat]

The earliest analysis of the order type of a countable nonstandard model of
arithmetic that I know of is due to Leon Henkin.  He describes the order
type in the last paragraph of his 1950 JSL paper "Completeness in the
theory of types" (volume 15, pp.81-91).

Skolem's 1934 paper is also referenced in Henkin's paper, but not in
connection with order types.

Ali Enayat