Metallica's sound has been described as heavy metal, thrash metal, hard rock, and speed metal. Metallica was influenced by early heavy metal and hard rock bands and artists Black Sabbath, Deep Purple, Kiss, Led Zeppelin, Queen, Ted Nugent, AC/DC, Rush, Aerosmith, Judas Priest, Scorpions and by new wave of British heavy metal (NWOBHM) bands Venom, Motörhead, Saxon, Diamond Head, Blitzkrieg, and Iron Maiden. Early punk rock bands Ramones, Sex Pistols, and the Misfits also influenced Metallica's style as did post-punk band Killing Joke and hardcore punk acts Discharge and Suicidal Tendencies. Lars Urlich multiple times cited Iron Maiden as probably the biggest influence on Metallica's career and the all further achievements. The band's early releases contained fast tempos, harmonized leads, and nine-minute instrumental tracks. Steve Huey of AllMusic said "Ride the Lightning" featured "extended, progressive epics; tight, concise groove-rockers". Huey said Metallica expanded its compositional technique and range of expression to take on a more aggressive approach in following releases, and lyrics dealt with personal and socially conscious issues. Religious and military leaders, rage, insanity, monsters, and drugsamong other themeswere explored on "Master of Puppets".