One of the more interesting artists who I’ve had the pleasure to meet is Frédéric Bruly Bouabré, also known as Cheick Nadro. He passed away in 2014 at the age of 90; his son Olivier called me with the sad news in January of that year. I was fortunate to have met with him in 2009 with the assistance of Francis Tagro Gnoleba and Tombekai Sherman at Bouabré’s house in Yopougon. A small sample of the iconic pictographic alphabet that he was inspired to invent can be found here. A more extensive review of the entirety of his work can be found in this four-volume text, published in 2013. The Yale copy is non-circulating, but scans of chapters may be requested. Other libraries that hold this work in the U.S. include Michigan State, Wisconsin, and Northwestern University. The text includes an extensive bibliography.
Update #1 (4/12/16): I believe the text linked to below has not been published anywhere; it is apparently a continuation from three cahiers written about by Théodore Monod and Denis Escudier. If I am mistaken and it has already been published, please contact me to let me know and I will comply with a request to take it down. I just talked with Olivier Bouabré, who asked me to send him a link, and I believe this is what he is looking for.
Update #2 (5/12/16): Audio recitation of the invented pictographic alphabet by Bouabré in his own voice, part 1:
and part 2: