Norbert Pearlroth, who combed hundreds of thousands of books in the New York Public Library over 52 years as sole researcher for ''Ripley's Believe It or Not,'' died of heart and kidney diseases Thursday at Maimonides Hospital in Brooklyn. He was 89 years old and lived in Brooklyn.
Mr. Pearlroth spent virtually seven days a week at the Main Library on Fifth Avenue in the years he worked for Ripley's, according to library officials. Every Friday he would turn in his research to the column.
According to Robert Whitman, a Ripley's spokesman, Robert Ripley, the founder of the feature, traveled to 198 countries to scout truths stranger than fiction. ''But his travels,'' Mr. Whitman said, ''were based on Mr. Pearlroth's research.''
Mr. Pearlroth was working in a bank in Manhattan in 1923 when he met Ripley, who was looking for someone who could read foreign journals. Mr. Pearlroth, who grew up in Poland and was fluent in 14 languages, was an avid reader of foreign publications and had an unusual memory for miscellany. Traveled World at Library
He stayed with the column after Mr. Ripley's death in 1947, when it was purchased by the King Features Syndicate. He retired in 1975.''Everyone has always believed that all of this information was found wandering the world,'' Mr. Pearlroth's son, Arthur, said yesterday from his home in Brooklyn. ''But it was really found on 42d Street and Fifth Avenue at the Main Library.''
''He would spend a great deal of time with the card catalogue and then sit in the reading room with these books for what seemed like days,'' said Catherine Marquard, supervising librarian in the general research section at the Main Library.
Friends at the library had planned to celebrate his 90th birthday next month. In addition to his son, Mr. Pearlroth is survived by his wife, the former Susan Wolf; a daughter, Sharon Goldberg, and two grandchildren.
Funeral services will be at noon today at the Kirschenbaum Funeral Home, 1153 Coney Island Avenue, at Avenue H, Brooklyn.

New York Times, 1983