NEW YORK, NY.- For the past year, celebrations of hip-hop’s first five decades have attempted to capture the genre in full, but some early stars and scenes all but disappeared long before anyone came looking to fete them. Three excellent books published in recent months take up the task of cataloging hip-hop’s relics, the objects that embody its history, before they slip away.

In the lovingly assembled, thoughtfully arranged “Do Remember! The Golden Era of NYC Hip-Hop Mixtapes,” Evan Auerbach and Daniel Isenberg wisely taxonomize the medium into distinct micro-eras, tracking innovations in form and also content — beginning with live recordings of party performances and DJ sets and ending with artists using the format to self-distribute and self-promote.

For more than a decade, cassettes were the coin of the realm in mixtapes, even after CDs usurped them in popularity: They were mobile, durable and easily duplicated. (More than one DJ rhapsodizes over the Telex cassette duplicator.)

Each new influential DJ found a way to push the medium forward — Brucie B talks about personalizing tapes for drug dealers in New York City’s Harlem; Doo Wop recalls gathering a boatload of exclusive freestyles for his “95 Live”; and in one memorable section, Harlem’s DJ S&S details how he secured some of his most coveted unreleased songs, sometimes angering the artists in the process.

The book covers some DJs who were known for their mixing, like Ron G, and some who were known for breaking new music, like DJ Clue. Some, like Stretch Armstrong & Bobbito, whose late-night radio shows were widely bootlegged before they began distributing copies themselves, managed both.

Mixtapes were big business — one striking two-page photo documents a handwritten inventory list from Rock ’n’ Will’s, a storied shop in Harlem, which showed the breadth of stock on display. Tape Kingz formalized and helped export mixtapes globally, and more than one DJ remarks about being shocked to see their tapes available for sale when they traveled to Japan.

Mixtapes were the site of early innovations that ended up crucial to the industry as a whole, whether it was proving the effectiveness of street-corner promotion or, via blend tapes in the late ’80s and early ’90s, setting the table for hip-hop’s cross-pollination with R&B.

Eventually, the format was co-opted as a vehicle for record labels like Bad Boy and Roc-a-Fella to introduce new music, or artists like 50 Cent and the Diplomats to release songs outside of label obligations. (The book effectively ends before the migration of mixtapes to the internet, and doesn’t include the contributions of the South.) Even now, the legacy of mixtapes endures, the phrase a kind of shorthand for something immediate, unregulated and possibly ephemeral. But “Do Remember!” makes clear they belong to posterity, too.

That same pathway from informal to formal, from casual art to big business, was traveled by hip-hop’s promotional merchandise, particularly the T-shirt. That story is told over and again in “Rap Tees Volume 2: A Collection of Hip-Hop T-shirts & More 1980-2005,” by well-known collector DJ Ross One.

It’s a pocket history of hip-hop conveyed through the ways people wanted to wear their dedication to it, and the ways artists wanted to be seen. By the mid-1980s, logos were stylized and stylish. Public Enemy, especially, had a robust understanding of how merchandise could further the group’s notoriety, captured here in a wide range of shirts and jackets.

In the 1980s, hip-hop hadn’t fully cleaved into thematic wings — tours often featured unexpected bedfellows. One tour shirt for the jovial Doug E. Fresh shows his openers included angsty agit-rap outfit Boogie Down Productions and ice-cold stoics Eric B. & Rakim.

Many of the shirts in the book were made by record labels for promotion, but there’s a robust bootleg section as well — see the hand-painted denim trench coat featuring Salt-N-Pepa — reflecting the untapped demand that remained long before hip-hop fashion was considered unassailable business.

This collection showcases some of hip-hop’s indelible logos: Nervous Records, the Diplomats, Loud Records, Outkast; shirts for radio stations and long-defunct magazines; impressive sections on Houston rap and Miami bass music; as well as promotional ephemera like Master P boxer shorts, a tchotchke toilet for Biz Markie and an unreleased Beastie Boys skateboard. That “Volume 2” is as thick as its essential 2015 predecessor is a testament to how much likely remains undiscovered, particularly from eras when archiving wasn’t a priority.

Some of the earliest hip-hop T-shirts in “Rap Tees” feature flocked lettering that is familiar from the backs of Hells Angels and B-boy crews. The aesthetic is the subject of “Heated Words: Searching for a Mysterious Typeface” by Rory McCartney and Charlie Morgan, a heroic work of sociology, archival research and history that traces the development of the style, from its historical antecedents to the actual locations in New York where young people would get their T-shirts customized to contemporary streetwear’s re-embrace of the form.

This typeface that, the authors discover, has no agreed-upon name (and also no fully agreed-upon back story) conveys “instant heritage,” typographer Jonathan Hoefler tells them. The lettering derives from black letter, or Gothic typefaces, but the versions that adorned clothes throughout the ’60s, ’70s and ’80s were often more idiosyncratic and, at times, made by hand.

The lettering style thrived thanks to the ease of heat-transfer technology, which allowed the DIY-inclined to embellish their own garments at will. It was embraced by car clubs and biker gangs (and, to a lesser extent, some early sports teams). Gangs were teams, too, of a sort, as were breakdancing crews. Shirts with these letters became de facto uniforms.

McCartney and Morgan spend a lot of time detailing how the letters themselves came to be and track down the places where they were turned into fashion — spotlighting one New York City store in the Bronx where many gangs would buy their letters, or the Orchard Street shop on the Lower East Side that provided letters for the Clash as well as shirts for Malcolm McLaren’s “Double Dutch” video and the cover of a local newspaper, East Village Eye.

“Heated Words” is relatively light on text: It draws its connections through imagery, both professional and amateur. The book is an impressive compendium of primary sources, many of which have not been seen before, or which have been public, but not viewed through this particular historical lens.

It’s a good reminder, along with “Do Remember!” and “Rap Tees,” that some elusive histories aren’t buried so much as they crumble into barely recognizable pieces. Devoted researchers like these can follow breadcrumb trails and piece together something like the full story, but some details remain forever out of reach, evaporated into yesteryear.

This article originally appeared in The New York Times.