Title: Opus musicum
Content:  Opus musicum is a publisher established in 1969 in Brno, Czech Republic. It focuses on publishing of a music magazine under the same name but has also its own book series called Opus Musicum Library. Since its foundation the OM Library has published 20 titles. The music magazine is published every two months and contains studies and essays on music and related cultural themes, articles, reviews, news.
Title: Opus (Eric Prydz song)
Content:  "Opus" is a song by Swedish DJ and producer Eric Prydz. It was released as a digital download on 27 July 2015 as the fourth single from his debut studio album Opus (2016). The song was written and produced by Eric Prydz and peaked at number three in Belgium.
Title: Opus (comic strip)
Content:  Opus is the title character and protagonist of the strip. Though he returned to Antarctica at the end of Outland, Opus traveled back home to Bloom County, only to find that time has changed everything and everyone he once held dear. His employment usually depended on the week's joke – since Opus began, he has so far been a political operative, a garbageman, and a newspaper ombudsman – but he was most often depicted as a syndicated cartoonist. While his mother, maiden name Bougm, was no longer "long-lost," she was not all he had imagined her to be after a decades-long search, and he was frequently seeking the comfort of an ideal mother-figure. In a 2003 interview with The A.V. Club, Breathed revealed that "Opus was named after a Kansas song." (The band's 1976 album Leftoverture includes the song "Opus Insert" and a suite called "Magnum Opus".) He also added, "If you're too young to know who Kansas was, to hell with you."
Title: Opus (comic strip)
Content:  Opus was a Sunday strip drawn by Berkeley Breathed from November 23, 2003, to November 2, 2008. It was Breathed's fourth comic strip, following The Academia Waltz, Bloom County and Outland. Set in Bloom County, the satirical strip featured Breathed's character Opus the Penguin It was launched on November 23, 2003, and was syndicated by The Washington Post Writers Group. In early October 2008 the author declared he was terminating the strip because of his expectation that the United States is going to face tough times and his desire to depart from his most famous character "on a lighter note".
Title: Opus (classical record magazine)
Content:  Opus was an American magazine that featured critical reviews of classical music recordings. Based in Harrisburg, Pennsylvania, the magazine ran from November/December 1984 to March/April 1988, publishing 21 issues. James R. Oestreich was its editor-in-chief. Historical Times, Inc., of Harrisburg was its owner. Warren Bertram Syer (1923–2007), who had published High Fidelity for 30 years, was then the president of Historical Times.
Title: Opus (classical record magazine)
Content:  Because Opus was founded by classical music journalists, it was a cause as much as it was a magazine. Besides shorter reviews, Richard Taruskin freely wrote as many as 60 pages on Beethoven symphony recordings, and Allan Kozinn wrote 82 pages on the state of the classical record business. Will Crutchfield and Conrad Osborne published a running debate about vocal style.
Title: Opus (Opus album)
Content:  Opus is the sixth studio album by Austrian pop rock band Opus. It was released in 1987. It peaked at #7 on the Ö3 Austria Top 40 Longplay. The first single "Whiteland", peaked at #3 on the Ö3 Austria Top 40 Singles and #2 on the Ö3-Hitparade. The second single, "Faster and Faster", peaked at #12 on the Ö3 Austria Top 40 Singles and #2 on the Ö3-Hitparade. The third single, "Will You Ever Know Me", peaked at #24 on the Ö3-Hitparade.
Title: Opus (Yugoslav band)
Content:  Opus was a Yugoslav progressive rock band formed in Belgrade in 1973. Formed and led by former YU Grupa keyboardist Miodrag "Mive" Okrugić, the band went through several lineup changes, its various lineups featuring notable musicians like guitarist Miodrag "Bata" Kostić, vocalist Dušan Prelević and guitarist Vidoja "Džindžer" Božinović. The band released only one studio album, ending their activity in 1979.
Title: Opus the Penguin
Content:  According to Opus' back story, he is from the Falkland Islands, How he got from there to Bloom county is explained in "The Night Of The Mary Kay Commandos". He was separated from his mother at a young age, and much of his personality is therefore enmeshed in his sense of abandonment and yearning for a mother figure. There is never any mention of Opus' father if he ever knew him. Over the years Opus has served as Steve Dallas' legal secretary, journeyed to Antarctica in search of his mother, played the tuba in heavy metal group Deathtöngue (later renamed Billy and the Boingers), wooed (and was nearly married to) an abstract sculptor 
Title: The Opus
Content:  The Opus is an American hip hop record production duo from Chicago, Illinois. It consists of The Isle of Weight and Mr. Echoes. AllMusic described them as "two of the most brilliant beatmakers working in hip-hop circa 2003." The Isle of Weight (born Aaron Smith) and Mr. Echoes (born Kevin Johnson) first met while attending Proviso East High School together. In 1994, the duo started making music together. The duo handled the production work on Rubberoom's 1999 album Architechnology.

Question: Who is the author of Opus?
Answer: Michael Hollinger.