Isaac's universe, book 3: Unnatural diplomacy
Robert Silverberg et Collectif1992

At the end of the second millenium, the five sentient species in the known universe that have achieved spaceflight are joined by a sixth -peculiar, warm-blooded creatures from a forgotten planet called Earth.
And in the dark and perilous void, a precarious truce is declared -as the galaxy's elite races, separate and distinct, confront the most difficult challenge of all...coexistence.

Prepare to enter a breathtaking cosmos born out of the genius of Isaac Asimov -and spectacularly realized by Hal Clement, George Alec Effinger, Karen Haber, Janet Kagan, Rebecca Ore, Harry Turtledove, Lawrence Watt-Evans

Titre original : Isaac's universe, book 3: Unnatural diplomacy (1992)