How can I find a specific person or family in the NY 1940 and 1950 census?

#1

Names are Gertrude Bartlett and her daughter Helen Bartlett (approximately 0-5 years old in 1940)

Living in New York, NY

#2

There are many restrictions that make identifying individual people in public use microdata impossible. First, the 1940 and 1950 census files are 1% samples of the population. Second, in both samples geographic areas are only identifiable if there are more than 100,000 individuals within the sample in that area.