Has Peter David ever put in any references to his early Trek work, i.e. his run on the first DC comics series and his early novels, in his New Frontier series?
Gleau the Selevian's species was introduced in "Strike Zone". That novel also features a now-grown Kobry (aka Moron, aka Bernie) the albino Klingon throwback, from PAD's TOS Series I comics for DC.
Kebron, McHenry, Soleta and Tobias were all introduced in the first three "Starfleet Academy" YA novels.
Arex and M'Ress timejumped from the 23rd century, essentially picking up on plans that were scuttled (DC Comics). For example, Arex moves to Security in the 24th century (PAD had planned a strong storyline for Arex in the Series II comic for DC, but it had to be given to Fouton instead).
In "Gateways: Cold Wars", Arex and M'Ress joke about Mr Bearclaw (from the TOS comic). Bearclaw donuts in the rec deck.
Morgan Korsmo is from "Vendetta".
Descendants of Boyajian and Meyer, of PAD TOS, are in PAD's 24th century works: