The term "retro-metal" has been applied to such bands as Texas based The Sword, California's High on Fire, Sweden's Witchcraft and Australia's Wolfmother. Wolfmother's self-titled 2005 debut album combined elements of the sounds of Deep Purple and Led Zeppelin. Fellow Australians Airbourne's début album Runnin' Wild (2007) followed in the hard riffing tradition of AC/DC. England's The Darkness' Permission to Land (2003), described as an "eerily realistic simulation of '80s metal and '70s glam", topped the UK charts, going quintuple platinum. The follow-up, One Way Ticket to Hell... and Back (2005), reached number 11, before the band broke up in 2006. Los Angeles band Steel Panther managed to gain a following by sending up 80s glam metal. A more serious attempt to revive glam metal was made by bands of the sleaze metal movement in Sweden, including Vains of Jenna, Hardcore Superstar and Crashdïet.
What album did AC/DC produce in 2007 that displayed their hard riffing tradition?