Citing graphviz in a paper

I used graphviz for an academic paper of a field that usually doesn't use visualization techniques.
I was asked by the journal editor to properly cite graphviz in the references with the author and year in addition to organization and URL. Does anyone knows about this?

The preferred citation

The preferred citation is

    author = {Emden R. Gansner and Stephen C. North},
    title = {An open graph visualization system and its applications to software engineering},
    year = {2000},
    volume = {30},
    number = {11},
    pages = {1203--1233}

and the URL is

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