1.   Locating these sources was intense, painstaking work that spanned two eras of information retrieval.

2.   The treatment of the man who killed Al Lowenstein spans an era of wholesale change in the insanity defense in America.

3.   They spanned two eras of the game in this country, the rising superstar and the old caddie.

4.   Kolya, a crocodile whose life spanned the eras of both czars and communists, has died of old age in the Urals city of Yekaterinburg.