The Kane Chronicles

The Kane Chronicles is a book triology written by Rick Riordan. It is hinted that it exists in the same universe as Percy Jackson and the Olympians and The Heroes of Olympus. It is a trilogy series. The books are The Red Pyramid, The Throne of Fire and The Serpent's Shadow.

Relationship with Percy Jackson and the Olympians
The series makes occasional references to the Percy Jackson and the Olympians series, as it takes place in the same world.
 * Towards the beginning of the book Amos states that Manhattan has its own set of gods and that they must be kept separate from Egyptian gods. He says this while looking at the Empire State Building, the current home of Mount Olympus.
 * When the Egyptian goddess Bast needed a portal she said that "I try to avoid Manhattan, but this is an emergency." She presumably wanted to avoid Manhattan because she knew that Olympus is there.
 * Later in the book, Thoth mentions that the Greeks confuse him with Hermes, something he takes offense to as Hermes is apparently of a very different person.
 * In the second book, The Throne of Fire, Carter catches a glimpse of a winged horse flying around Manhattan, and recalls what Amos said about Manhattan and its gods. It is unknown however if the pegasus was Blackjack, the original Pegasus, or simply a pegasus that lives around New York City.
 * Nico di Angelo mentions having traveled to a graveyard in New Orleans. In the Kane series, there is a graveyard in New Orleans that connects to the Hall of Judgement, a place for the dead to be judged by Anubis.
 * In flashbacks, Bes was shown fighting demons during World War II, a conflict started by demigod sons of the Big Three, as well as dressed in a Roman toga with Tarawet.

Relationship with The Heroes of Olympus
The triology makes occasional references to the Heroes of Olympus, being in the same world.
 * In The Throne of Fire, Sadie met several Roman mummies who used the Di immortals swear and mentioned Pluto, Jupiter, and Vulcan. Later, the God Ptah mentioned that they went on to 'whatever afterlife they were destined for' referring to the Underworld.
 * Drew and Lacy appear as Sadie's schoolmates in America, mentioning they go to the same summer camp during The Serpent's Shadow. They are later mentioned to go to some sort of camp, which is Camp Half-Blood . Drew's and Lacy's personalities stay the same.
 * Sadie also describes "rival magicians and gods as close as Long Island," a reference to the gods in Manhattan and their demigod children at Camp Half-Blood in Long Island.
 * The Williamsburg Bridge has appeared in both series.
 * The Rosetta Stone used Greek to translate it.