You tried going to https://www.artsbma.org/wp/collectionitemdetails?searchlayout=grid&showform=0&ordering=popular&searchphrase=exact&areas%5B0%5D=portfolio&searchartistname=William%20Christenberry,%20United%20States,%20(born%201936)&areas%5B%5D=portfolio&searchlayout=details&limit=1&start=1, and it doesn't exist. All is not lost! You can search for what you're looking for.