Background: Art Spiegelman (; born Itzhak Avraham ben Zeev on February 15, 1948) is an American cartoonist, editor, and comics advocate best known for his graphic novel Maus. His work as co-editor on the comics magazines Arcade and Raw has been influential, and from 1992 he spent a decade as contributing artist for The New Yorker, where he made several high-profile and sometimes controversial covers. He is married to designer and editor
Context: Hired by Tina Brown as a contributing artist in 1992, Spiegelman worked for The New Yorker for ten years. Spiegelman's first cover appeared on the February 15, 1993, Valentine's Day issue and showed a black West Indian woman and a Hasidic man kissing. The cover caused turmoil at The New Yorker offices. Spiegelman intended it to reference the Crown Heights riot of 1991 in which racial tensions led to the murder of a Jewish yeshiva student. Spiegelman had twenty-one New Yorker covers published, and submitted a number which were rejected for being too outrageous.  Within The New Yorker's pages, Spiegelman contributed strips such as a collaboration titled "In the Dumps" with children's illustrator Maurice Sendak and an obituary to Charles M. Schulz titled "Abstract Thought is a Warm Puppy". An essay he had published there on Jack Cole, the creator of Plastic Man, called "Forms Stretched to their Limits" was to form the basis for a book in 2001 about Cole called Jack Cole and Plastic Man: Forms Stretched to their Limits.  The same year, Voyager Company published a CD-ROM version of Maus with extensive supplementary material called The Complete Maus, and Spiegelman illustrated a 1923 poem by Joseph Moncure March called The Wild Party. Spiegelman contributed the essay "Getting in Touch With My Inner Racist" in the September 1, 1997 issue of Mother Jones.  Spiegelman's influence and connections in New York cartooning circles drew the ire of political cartoonist Ted Rall in 1999. In an article titled "The King of Comix" in The Village Voice, Rall accused Spiegelman of the power to "make or break" a cartoonist's career in New York, while denigrating Spiegelman as "a guy with one great book in him". Cartoonist Danny Hellman responded by sending a forged email under Rall's name to thirty professionals; the prank escalated until Rall launched a defamation suit against Hellman for $1.5 million. Hellman published a "Legal Action Comics" benefit book to cover his legal costs, to which Spiegelman contributed a back-cover cartoon in which he relieves himself on a Rall-shaped urinal.  In 1997, Spiegelman had his first children's book published: Open Me... I'm a Dog, with a narrator who tries to convince its readers that it is a dog via pop-ups and an attached leash. From 2000 to 2003 Spiegelman and Mouly edited three issues of the children's comics anthology Little Lit, with contributions from Raw alumni and children's book authors and illustrators.
Question: what else did he do at the new yorker?

Answer:
Within The New Yorker's pages, Spiegelman contributed strips such as a collaboration titled "In the Dumps" with children's illustrator Maurice Sendak