Question: What is the book series, written by Cecily von Ziegesar, that the character Eric van der Woodsen appears in?

Context paragraphs:
The It Girl (novel series): The It Girl is a series of novels created by bestselling novelist Cecily von Ziegesar.  The series is ghostwritten from the original idea by von Ziegesar.  The series, aimed toward young adults, is a spin-off from the bestselling "Gossip Girl" series.

Gossip Girl (novel series): Gossip Girl is an American young adult novel series written by Cecily von Ziegesar and published by Little, Brown and Company, a subsidiary of the Hachette Group.  The series revolves around the lives and romances of the privileged teenagers at the Constance Billard School for Girls, an elite private school in New York City's Upper East Side.  The books primarily focus on best friends Blair Waldorf and Serena van der Woodsen, whose experiences are among those chronicled by the eponymous gossip blogger.  The novel series is based on von Ziegesar's experiences at Nightingale-Bamford School and on what she heard from friends.

Gossip Girl (season 4): The fourth season of "Gossip Girl", an American teen drama, consisted of 22 episodes which aired between September 13, 2010 and May 16, 2011.  The series was based upon the book series by Cecily von Ziegesar and developed for television by Josh Schwartz and Stephanie Savage.  The CW renewed the series for a full fourth season on February 16, 2010.  Blake Lively, Leighton Meester, Penn Badgley, Chace Crawford, Taylor Momsen, Ed Westwick, Jessica Szohr, Kelly Rutherford, and Matthew Settle all return as series regulars.

List of Gossip Girl episodes: "Gossip Girl" is a teen drama which premiered on September 19, 2007 in the United States on The CW.  "Gossip Girl" is based on the young-adult book series of the same name written by Cecily von Ziegesar, and was developed for television by "The O.C." creators Josh Schwartz and Stephanie Savage.  The series follows the lives of the young, wealthy, and social elite residing in the Upper East Side of Manhattan, and is narrated by an unseen and seemingly omniscient character, "Gossip Girl", whose blog is widely read among the characters.

Reckless (von Ziegesar novel): Reckless is the third book in the The It Girl novels by the German American author Cecily von Ziegesar.  The series is ghostwritten from the original idea by Ziegesar.  The series, aimed toward young adults, is a spin-off from the bestselling "Gossip Girl" series.  It was released in 2006 by Little, Brown.

Eric van der Woodsen: Eric van der Woodsen (spelled Erik in the novels) is a fictional character from the book series "Gossip Girl" and the television series of the same name, in which he is portrayed by Connor Paolo.

List of Gossip Girl characters: The following is a list of characters for The CW teen television drama series, "Gossip Girl".  The show is based on the popular book series of the same name, written by author Cecily von Ziegesar.

Gossip Girl (season 1): The first season of "Gossip Girl", an American teen drama based upon the book series by Cecily von Ziegesar.  Developed for television by Josh Schwartz and Stephanie Savage.  Airing on The CW from September 19, 2007 till May 19, 2008 with 18 episodes.  It tells the story of Serena van der Woodsen's return to Manhattan's Upper East Side in New York City following her mysterious disappearance to boarding school in Connecticut, while being watched by gossip website Gossip Girl.

Gossip Girl: Gossip Girl is an American teen drama television series based on the book series of the same name written by Cecily von Ziegesar.  The series, created by Josh Schwartz and Stephanie Savage, originally ran on The CW for six seasons from September 19, 2007, to December 17, 2012.  Narrated by the omniscient blogger "Gossip Girl", voiced by Kristen Bell, the series revolves around the fictional lives of upper-class adolescents living in Manhattan's Upper East Side.

Lola Rhodes: Charlotte "Lola" Rhodes is a recurring character who exclusively appeared in the "Gossip Girl" television adaptation.  Created by series producer Joshua Safran, Lola Rhodes is portrayed by actress Ella Rae Peck.  The character of Charlotte "Charlie" Rhodes was initially introduced in the second half of season four, though this was later revealed to be Ivy Dickens, a struggling actress paid to impersonate her so that her mother, Carol Rhodes, could gain access to Lola's trust fund.  Ella Rae Peck later appeared during the second half of the fifth season to portray the role.  Lola is the cousin and biological half sister, technically three-quarter sister, of Serena van der Woodsen (Blake Lively) as a result of William van der Woodsen's (William Baldwin) affair with Lily Humphrey's sister, Carol Rhodes (Sheila Kelley).

Supporting paragraphs: Eric van der Woodsen Gossip Girl (novel series)
Answer: Gossip Girl