Sí by Néstor Barreto (Terranova, 2006).
Néstor Barreto (1952—) is described on one of his online bios as a heuristic poet, a word I had to look up. It means experimentally inventive, something to do with trial and error more or less, and that seems to be a great description for this poet. He has five books of poems currently available (this is the latest) and one forthcoming from a series called Colleción Maravilla (book trailer here). He’s the founder of Quimera Editores, which looks like they do a lot of visual art books (graffiti, comics). He was included in Papiros de Babel: antología de la poesía puertorriqueña en Nueva York By Pedro López-Adorno (Universidad de Puerto Rico, 1991). As far as I can tell, none of his work has been translated into English, though he includes on the last page of Sí his translation of a Marianne Moore poem so my guess is his English is pretty good.
His work is definitely experimental, which reads to me as a sometimes really interesting and sometimes not-quite-there thing. In this collection (and I think throughout the work I’ve been able to find) he’s obviously interested in playing with typography. He oscillates between verse and prose in this collection. The book seems varied, in style, and in achievement, and I think it will be difficult to read, but there are probably some really exciting poems in here if I can find them.