HK (Heinz Karl) Gruber
- Biography by Rudolph Illavsky at the Classical Composers Database notes Gruber's talents in other musical areas, his sense of humor, and membership in die reihe and the Radio Symphony Orchestra of Vienna.
- http://www.classical-composers.org/comp/gruber

Gruber, Heinz Karl
- Biography noting studies and teachers, instrumental background, and major works from the Grove Concise Dictionary of Music entry at WQXR radio.
- http://www.wqxr.com/cgi-bin/iowa/cla/learning/grove.html?record=3895

HK Gruber in Focus
- Introduction to his music by Paul Driver for Boosey & Hawkes. Emphasis given to his dark sense of humor and often unpredictable style.
- http://www.boosey.com/publishing/pages/composer/composerinfocus.asp?composerid=2843&langcode=gbr

A Pig Is a Pig Is a Pandemonium: HK Gruber
- Review of the music theatre comedy Gloria: A Pigtale by Paul Hertlendy blends the composer's sense of humor with that of the reviewer.
- http://www.artssf.com/aspen0504.html

Crumbling of A Great Wall of Music
- Sample of the work of Newsday critic Justin Davidson concerning the conducting and composition of H.K. Gruber. Cited by the 2002 Pulitzer Prize committee for his award in criticism.
- http://www.pulitzer.org/year/2002/criticism/works/042201.html