Title: Dark nebulae, globules, and protostars
Subjects: Bolvormige sterrenhopen, Interstellar matter, Nevels (astronomie), Galaxies, Protostars, Matiere interstellaire, Protosterren, Etoiles, Protostern
People: Bart J. Bok (1906-1983), Bart Jan Bok (1906-1983)