See bio under Sylvia Engdahl. (Her middle name was used only on some hardcover editions of her Young Adult novels. Her novels for adults therefore are not included in lists where it appears.)
Almost all nonfiction books that appear under her name were edited, not authored, by her.
"Lou Gehrig's Disease: Each volume in this timely series provides essential information on a disease or disorder (symptoms, causes, treatments, cures, etc.); presents the controversies surrounding causes, alternative treatments, and other issues"--