Lars Gustav Gabriel Hollmer (21 July 1948 – 25 December 2008) was a Swedish accordionist, keyboardist and composer, whose work drew on music ranging from Nordic folk tunes to progressive rock. He has been a member and/or founder of over half a dozen groups, most of whose work has been recorded at The Chickenhouse, his well outfitted home studio in his hometown of Uppsala. His work with the band Samla Mammas Manna, in the late 1960s and early 1970s and up to 2002, when the re-formed group played at the two-day ProgDay festival in North Carolina, was and is considered progressive rock.
https://en.wikipedia.org/wiki/Lars_Hollmer