Have you done the basic Books-in-Print search under author and subject? Also the major publishers are limited. Del Ray seems to be publishing Cthulhu stuff again. Little publishers abound and a lot of stories that are Cthulhu related don't necessary show up- for instance Stephen King's Jerusalem's Lot in Night Shift is Lovercraft.
Here's a quick look from my local library on Lovecraft-
Author: De Camp, L. Sprague (Lyon Sprague),
Title: Blond barbarians & noble savages / L. Sprague de Camp.
Author: Pagetti, Carlo.
Title: Cittadini di un assurdo universo : Poe, Mark Twain, Bierce, Lovecraft, Burdekin.
Title: An Epicure in the terrible : a centennial anthology of essays in honor of H.P. Lovecraft
Title: Eternal Lovecraft : the persistence of HPL in popular culture / edited by Jim Turner.
Author: Montaclair, Florent.
Title: Fantastique et événement : étude comparée des
oeuvres de Jules Verne et de Howard P. Lovecraft /
Florent Montaclair
Title: The Ghost.
Title. P. Lovecraft.
Publication info: [Paris, L'Herne, 1969]
Author: Joshi, S. T., 1958-
Title: H.P. Lovecraft / S.T. Joshi.
Author: Cannon, P. H. (Peter H.)
Title: H.P. Lovecraft / by Peter Cannon.Publication info: Boston : Twayne Publishers, c1989.
Author: Burleson, Donald R.
Title: H.P. Lovecraft, a critical study / Donald R. Burleson.
Author: Science Fantasy Society.
Title: H.P. Lovecraft: a symposium. Panelists: Fritz Leiber
[and others] Annotations:
Title: The H. P. Lovecraft companion / Philip A. Shreffler.
Publication info: Westport, Conn. : Greenwood Press, 1977.
Author: Houellebecq, Michel.
Title: H.P. Lovecraft : contre le monde, contre la vie /
Michel Houellebecq.
Author: Joshi, S. T., 1958-
Title: An H.P. Lovecraft encyclopedia / S.T. Joshi and David E. Schultz.
Title: H. P. Lovecraft, four decades of criticism / edited by S. T. Joshi.
Title: Howard Phillips Lovecraft memorial symposium / [ed. By Steve Eisner].
Author: Lovecraft, H. P. (Howard Phillips), 1890-1937.
Title: Lord of a visible world : an autobiography in letters/ H.P. Lovecraft ; edited by S.T. Joshi and David E. Schultz.
Author: De Camp, L. Sprague (Lyon Sprague), 1907-
Title: Lovecraft; a biography, by L. Sprague de Camp.Edition: [1st ed.]
Author: Lévy, Maurice.
Title: Lovecraft, a study in the fantastic / Maurice Lévy ;
ranslated by S.T. Joshi.
Author: Lovecraft, H. P. (Howard Phillips), 1890-1937.
Title: Lovecraft at last / by H.P. Lovecraft and Willis Conover ; with a new introduction by S.T. Joshi; foreword by Harold Taylor.
Author: Lovecraft, H. P. (Howard Phillips), 1890-1937
Title: The Lovecraft collector's library / edited by George Wetzel.
Author: Burleson, Donald R.
Title: Lovecraft : disturbing the universe / Donald R.
Author: Lévy, Maurice.
Title: Lovecraft, ou, Du fantastique / Maurice Lévy.
Title: Lovecraft's legacy / edited by Robert E. Weinberg,
Title: The new Lovecraft circle / edited by Robert M. Price.Author: Parsons, Judith Firestone.
Title: The rhetoric of science fiction in H. P. Lovecraft.
Title: Rhode Island on Lovecraft / edited by Donald M. Grant and Thomas P. Hadley ; illustrated by Betty Wells
Author: St. Armand, Barton Levi.
Title: The roots of horror in the fiction of H. P. Lovecraft
Author: Oakes, David A., 1968-
Title: Science and destabilization in the modern American
Author: Lovecraft, H. P. (Howard Phillips), 1890-1937.
Title: Selected letters.
Author: Derleth, August William, 1909-1971.
Title: Some notes on H. P. Lovecraft,
Author: Joshi, S. T., 1958-
Title: A subtler magick : the writings and philosophy of H.P.Lovecraft
Author: De Turris, Gianfranco, 1944-
Title: L'ultimo demiurgo e altri saggi lovecraftiani /Gianfranco de Turris & Sebastiano Fusco ; introduzione di Antonio Faeti.
