Commentary on interstellar matter associated with 18 open clusters /

"September 1989"--Cover.

The complex broad-band X-ray spectra of Seyfert galaxies /

Cover: Laboratory for High Energy Astrophysics.

A new general catalogue of nebulae and clusters of stars, being the catalogue of the late Sir John F.W. Herschel.

Mode of access: Internet.

Uranography ; or, a description of the heavens; designed for academies and schools; accompanied by an atlas of the heavens, showing the places of the principal stars, clusters, and nebulæ /

Mode of access: Internet.

Life and writings of George W. Abell:

Mode of access: Internet.