Dolly Parton and Marty Robbins are the latest country artists to be anthologized by Legacy Recordings. The two-CD sets will be released June 28. The Essential Marty Robbins includes 40 songs (including 16 No. 1 hits) spanning his 30-year career, while The Essential Dolly Parton collects 37 tracks from 1967 to 2001. ... In related news, Legacy Recordings has postponed the reissues of three Rosanne Cash studio albums until August.