1. ANDERSSON , P. O. , JELENSKI , A. , and KOLLUERQ , E. , 1972 , Research Report No. 107 , Research Laboratory of Electronics and Onsala Space Observatory, Chalmers University of Technology , Gothenburg , Sweden .
2. ANDEKSSOX , P. O. , JELENSKI , A. , and LUNDIN , A. , 1972 , Research Report No. 112 , Research Laboratory of Electronics and Onsala Space Observatory. Chalmers .
3. Chromium‐Doped Titania as a Maser Material