The New Kids on the Block album “Hangin’ Tough’’ will be the subject of a 33? book to be released by Bloomsbury Publishing on April 21. It’s a very big deal for the locally bred boy band. Other artists profiled in the series, which has respected musicians and journalists writing about iconic albums, include Dusty Springfield, whose “Dusty in Memphis’’ was profiled by Warren Zanes; the Replacements’ “Let It Be,’’ which was taken on by Decemberists frontman Colin Meloy, and Bob Dylan, whose “Highway 61 Revisited’’ had its 33? book written by Mark Polizzotti, director of the publication program at the Metropolitan Museum of Art in New York. The author of the New Kids book is Rebecca Wallwork, director of content strategy for Loews Hotels & Resorts, who was once the music editor at Interview magazine. Her “Hangin’ Tough’’ chapter titles will include “Rise N’ Grind,’’ “Let’s Get This,’’ and “BH Love Eternal.’’ (BH stands for “blockhead.’’) The 33? series is named after the speed of an LP album.