Quotes from a book with multiple authors

[Christoph]

So I want to add a quote but I do not want to attribute it to only one author, is there a way to link the quote to multiple authors simultaneously without putting a separate entry? Better yet is there a way to do attribute the quote to the book directly? Thanks for any info.

The quote is the following from the Difference Engine co-wrote by William Gibson and Bruce Sterling:

It is 1991. It is London. Ten thousand towers, the cyclonic hum of a trillion twisting gears, all air gone earthquake-dark in a mist of oil, in the frictioned heat of intermeshing wheels. Black seamless pavements, uncounted tributary rivulets for the frantic travels of the punched-out lace of data, the ghosts of history loosed in this hot shining necropolis. Paper-thin faces billow like sails, twisting, yawning, tumbling through the empty streets, human faces that are borrowed masks, and lenses for a peering Eye. And when a given face has served its purpose, it crumbles frail as ash, bursting into a dry foam of data, its constituent bits and motes. But new fabrics of conjecture are knitted in the City's shining cores, swift tireless spindles flinging off invisible loops in their millions, while in the hot unhuman dark, data melts and mingles, churned by gear-work to a skeletal bubbling pumice, dipped in a dreaming wax that forms a simulated flesh, perfect as thought--

[Paula]

There is no way to attribute to multiple authors unless you write in the bottom of text box. The book will have a primary author and a secondary author assigned. If you enter the Primary author in the author field, a list of all the books assigned to that author will display and you can select the appropriate book.

Edit to add - William Gibson is the primary author so to attach the quote to the book you will need to select him in the author field