Ursula Nordstrom, 78, an award-winning editor of children’s books who handled the works of such authors as E.B. White, Maurice Sendak and Laura Ingalls Wilder. Miss Nordstrom, who was formerly publisher and editor and chief of juvenile books at Harper & Row, edited White’s first children’s book, “Stuart Little,” in 1945. Seven years later, White presented her with his only copy of what became his classic “Charlotte’s Web.” She also published Sendak’s “Where the Wild Things Are,” filled with the aggressive beasts of children’s fantasies, after other publishing houses had rejected it. “With her incomparable editorial genius, Ursula Nordstrom transformed the American children’s book into a genuine art form,” Sendak said. Her other authors included Laura Ingalls Wilder, who wrote the autobiographical “Little House on the Prairie” series. Miss Nordstrom began at Harper & Row in 1936. She became head of the children’s book department in 1940 and in 1960 became the publishing company’s first female vice president. Her books have won numerous awards, including three Newbury Medals and two Caldecott Medals, the most prestigious children’s book awards. In New Milford, Conn. on Tuesday of ovarian cancer.