You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Private_school

Context:
Private schooling in the United States has been debated by educators, lawmakers and parents, since the beginnings of compulsory education in Massachusetts in 1852. The Supreme Court precedent appears to favor educational choice, so long as states may set standards for educational accomplishment. Some of the most relevant Supreme Court case law on this is as follows: Runyon v. McCrary, 427 U.S. 160 (1976); Wisconsin v. Yoder, 406 U.S. 205 (1972); Pierce v. Society of Sisters, 268 U.S. 510 (1925); Meyer v. Nebraska, 262 U.S. 390 (1923).

Question:
What is the citation for the Pierce v. Society of Sisters case?

268 U.S. 510