Rebuffed by earlier offers, Public Storage Inc. said today it has retained investment advisor Goldman, Sachs & Co. to assist with its efforts to acquire Shurgard Storage Centers Inc. “We are disappointed that Shurgard’s board continues to refuse to sit down with us to explore the potential of a mutually beneficial transaction, despite the overwhelmingly positive response from shareholders and analysts to our proposal,” said Public Storage CEO Ronald L. Havner, Jr. in a statement. “It remains our preference to work cooperatively with Shurgard to effectuate this transaction.” Earlier this month, Glendale-based Public Storage offered to acquire Shurgard in a stock swap valued at about $2.49 billion at the time. The Shurgard board rejected the offer saying it was not in the best interests of shareholders. Following the offer, Shurgard’s shares soared by $6.10 to $53 per share. This morning, Shurgard shares opened at $25.74 and remained relatively unchanged by mid-day. Public Storage shares rose to $66.02 after opening at $65.28 per share this morning.