Simplify the following text for a Grade 8 native English-speaking person.
Original: His writings about the effects of racial segregation were used as evidence in the landmark Supreme Court case Brown v. Board of Education , and part of his 1966 book A Sign for Cain dealt with the involvement of medical professionals in the Holocaust .
Simplified: His writings about the effects of racial segregation were evidence in the important Supreme Court case Brown v. Board of Education . Part of his 1966 book , A Sign for Cain , was about medical professionals and their actions in the Holocaust .