Before the Knoedler Gallery closed its doors last year, and before it and its former president Ann Freedman were mired in lawsuits and accusations of selling fakes, the gallery on East 70th Street in Manhattan was considered among the most distinguished in the world.

Formed 165 years ago, the gallery helped shape many of this country’s greatest collections, including those of Paul Mellon, Henry Clay Frick and Robert Sterling Clark. Over the years Knoedler also bought and sold works by a roster that reads like a Who’s Who of 19th- and 20th-century art, including van Gogh, Manet, Winslow Homer, Frederic E. Church and John Singer Sargent, as well as more contemporary figures like Louise Bourgeois, Willem de Kooning and Barnett Newman.

This week the Getty Research Institute in Los Angeles announced that it had bought the Knoedler Gallery archive, a vast trove dating from around 1850 to 1971 that incorporates stock books, sales books, a photo archive and files of correspondence, including illustrated letters from artists and collectors....