Rubin said it sounds like the four guys in Black Sabbath getting together and playing, and Butler agreed.

CNN: Black Sabbath announce new album produced by Rick Rubin

There is a brief respite when the boys daringly enter Black Sabbath territory for a comparatively laid-back rendition of Sabbra Cadabra, with its easy riffs and lazy drums.

BBC: Garage Inc - Metallica

Drawing from sources as disparate as Black Sabbath, the indie-instrumentalists in Tortoise and the self-flagellating noise-masters in Swans, Pelican makes instrumental hard rock that whispers as much as it shouts, and teases as much as it pummels.

NPR: Instrumental Hard Rock, Teasing as It Pummels

The hired DJ seemed at one stage to have a passion for educating the younger generations in the ways of Deep Purple and Black Sabbath.

BBC: Diary of a street party, part 3

The band Earth got its start in the early '90s, specializing in the drones of experimental feedback like Black Sabbath with fewer notes and no drummer.

NPR: Earth: The Sound of Desert-Swept Doom

One US newspaper described it as embracing "everything from country-tinged ditties to Black Sabbath-style fuzzbuckets with the Paul McCartney songbook tossed in to throw the dogs off the scent".

BBC: The White Stripes: Raw Rock Revivalists

Black Sabbath guitarist Tony Iommi has written the song which will represent Armenia in the Eurovision Song Contest.

BBC: Sabbath star Tony Iommi pens Armenian Eurovision entry

The state of heavy metal may be in question, but partisans can agree on one thing: The form's roots are located in the chugging guitar and wailing vocals of two bands: Led Zeppelin and Black Sabbath.

NPR: Kicking and Screaming, Metal Back in Music Spotlight

The festival, now in its tenth year, is headlined by Metallica, Prodigy and Black Sabbath.

BBC: Download Festival: Motorists warned over delays