Issue #90 of Campaign magazine (March April 1979) featured a close look at Tobruk.

Contents:
The Weapons and Tactics of Tobruk * Lorrin Bird
Additions to War of the Ring * Don Lowry
The Confederate Navy, 1861-1865 * John W. Mauzey, Jr.
Napoleon: In the Strategic Sense * Michael E. Crane
Some Strategic and Tactical Hints to Overlord * Jack Greene, Jr.
Impressions From the Prism * Jeffery Paul Jones
Thumbnail Analysis * Don Lowry
Book Review * Don Lowry
G2 Reports * Editor
Mail Call

Available on Wargame Vault.