The universe of stars : based on radio talks from the Harvard Observatory - Gerrish, Willard Peabody; King, Edward Skinner, 1861-1931; Luyten, Willem Jacob, 1899-1994; Payne, Cecilia Helena, 1900-1979; Shapley, Harlow, 1885-1972 (Cambridge (Mass) : The Observatory, 1929)