SAN FRANCISCO?- Two stolen Italian books dating to the 17th century that were discovered in California and many other plundered ancient artifacts will be returned to their country of origin, federal officials say.

The books, "Stirpium Historiae" and "Rariorm Plantarum Historia Anno 1601," were taken from Italy's Historical National Library of Agriculture and sold to an antiquities dealer in Italy, Immigration and Customs Enforcement said in a statement. The San Francisco Bay Area buyer willingly surrendered the books to investigators.

ICE's Homeland Security Investigations unit will return other cultural treasures to the Italian government this week, including a 17th century cannon, 5th century Greek pottery and items dating to 300-460 BC.

The items were stolen in Italy and smuggled into the US over the last several years. Their value was not released.

"The cultural and symbolic worth of these Italian treasures far surpasses any monetary value to the Italians," Tatum King, acting special agent in charge of Homeland Security Investigations in San Francisco said in the statement.

Agents also recovered four stolen artifacts reported missing in July 2012. Three Roman frescos dating to 63-79 AD and a piece of dog-figure pottery from the 4th century BC that were illegally pilfered from Pompeii were recovered from a private art collection in San Diego and will be returned to Italy.

Eleven investigations nationwide led to the recovery of the antiquities. US Customs and Border Protection and Rome's force for combatting art and antiquities crimes helped Homeland Security Investigations officials in New York, Boston, Baltimore, Miami, San Diego and San Francisco.

"This repatriation underscores the strong level of judicial cooperation between the US and Italy, and the great attention that both countries assign to the protection of cultural heritage," said Claudio Bisogniero, Italy's ambassador to the US.

The US government has returned more than 7,200 artifacts to 30 countries since 2007, including paintings from France, Germany, Poland and Austria; 15th to 18th century manuscripts from Italy and Peru; and items from China, Cambodia and Iraq, the statement says.