Question: Who had Tina Tchen as a Chief of Staff and started her early legal career working at the law firm Sidley Austin?

Context articles: D. Cameron Findlay
R. Eden Martin
Irma Carrillo Ramirez
Karen Gren Scholer
Marcos Rodriguez Ema
Tomoo Nishikawa
Michelle Obama
Sidley Austin
Tina Tchen
Brown &amp; Wood

D. Cameron Findlay is an American attorney who is the senior vice president, general counsel, and secretary of Archer Daniels Midland Company, the global agriculture business giant ranked 28th on the Fortune 500 list of largest American companies.
 He joined ADM in 2013.
 Prior to that, he served from 2009-13 as senior vice president, general counsel, and secretary of Medtronic, Inc., the world's largest medical device company.
 Before his time at Medtronic, he was executive vice president and general counsel for Aon Corporation for six years.
 Previously he served as Deputy Secretary of Labor from 2001 to 2003 in the administration of George W. Bush and as a member of the board of directors of the Overseas Private Investment Corporation.
 Prior to that, he was a partner in the law firm of Sidley Austin, a senior White House aide to President George H.W. Bush.
R. Eden Martin is an American lawyer.
 Martin was a partner at the law firm Sidley Austin LLP from 1975 to 2004.
 Martin has served as President of The Commercial Club of Chicago since 1999.
 He is a member of the Boards of Directors of the Chicago Board Options Exchange, and Nicor Inc., a Life Trustee of the Chicago Symphony Orchestra and a member of the Board of Trustees of Northwestern University.
 He has been an Aon Corporation director since 2002 and serves as Chairman of Aon Foundation.
 He has also served on the boards of the University of Illinois Foundation, the Chicago History Museum, and the Ravinia Festival.
Ramirez was born in 1964.
 She received a Bachelor of Arts degree in 1986 from the West Texas A&M University.
 She received a Juris Doctor in 1991 from the Southern Methodist University Dedman School of Law.
 Judge Ramirez began her legal career working as an associate for the law firm Locke Purnell Rain Harrell, PC (now Locke Lord LLP) from 1991 to 1995.
 She served as an Assistant United States Attorney for the United States Attorney’s Office for the Northern District of Texas, working in the Civil Division from 1995 to 1999 and the Criminal Division from 1999 to 2002.
Scholer received a Bachelor of Arts degree in 1979 from Rice University.
 She received a Juris Doctor in 1982 from Cornell Law School.
 She started her legal career as an associate at the law firm of Strasburger & Price, LLP, where she was employed from 1982 to 1996.
 She was elevated to partner in 1989.
 From 1996 to 2000, she was a partner at the law firm of Andrews & Kurth, LLP.
 From 2001 to 2008, she served as a State District Judge for the 95th Judicial District Court of Dallas County.
 In 2007, she also served as the Presiding Judge for the Dallas County Civil District Judges.
 From 2009 to 2013, she was a partner at the law firm of Jones Day.
 Since 2014, she has been a principal in the law firm of Carter Scholer Arnett Hamada & Mockler, PLLC, where she specializes in business litigation, complex tort litigation, and alternative dispute resolution.
 She was appointed as a co-managing partner in 2015.
After graduating with honors from Georgetown University’s School of Foreign Service and completing his juris doctor degree at Georgetown University Law Center in Washington, D.C., Mr. Rodríguez-Ema returned to Puerto Rico to work as an associate in the corporate and banking division of a major law firm in San Juan.
 He concentrated and focused his early legal career on the legal aspects of complex financial transactions for the law firm’s banking clients.
 He was later recruited by Drexel Burnham Lambert-Puerto Rico as a Vice President, later Senior Vice President, of their Corporate and Municipal Finance division.
 He was responsible for structuring and executing a variety of bond and note issues for the Government of Puerto Rico, its several dependencies, as well as for Drexel’s private clients.
 In 1989 Mr. Rodríguez-Ema was recruited by Chase Manhattan Bank in Puerto Rico to manage the investment banking unit of its Chase Securities Puerto Rico subsidiary, thus becoming a member of Chase’s Management Committee in Puerto Rico.
 After the November 1992 election, the governor-elect of Puerto Rico asked him to join his fiscal and financial team as President of the Government Development Bank for Puerto Rico (GDB).
 The GDB (www.gdb-pur.com) is the bank and fiscal agent for the government of Puerto Rico.
 As such, it is chartered with the coordination, structure, execution and placement of every single financing, bond or note issue for all government agencies, government-owned corporations and its multiple dependencies, including all 78 municipalities throughout Puerto Rico.
Tomoo Nishikawa (西川 知雄) is a Japanese attorney and former politician.
 He currently heads the Tokyo office of Sidley Austin (Sidley Austin Nishikawa), and previously served for one term in the House of Representatives.
Michelle LaVaughn Robinson Obama (born January 17, 1964) is an American lawyer and writer who was First Lady of the United States from 2009 to 2017.
 She is married to the 44th President of the United States, Barack Obama, and is the first African-American First Lady.
 Raised on the South Side of Chicago, Illinois, Obama is a graduate of Princeton University and Harvard Law School, and spent her early legal career working at the law firm Sidley Austin, where she met her husband.
 She subsequently worked as the Associate Dean of Student Services at the University of Chicago and the Vice President for Community and External Affairs of the University of Chicago Medical Center.
 Barack and Michelle married in 1992 and have two daughters.
Sidley Austin LLP, formerly known as Sidley Austin Brown & Wood LLP, is the sixth-largest U.S.-based corporate law firm with 1,900 lawyers and annual revenues of more than one billion dollars.
 The firm is one of the highest paying companies in the U.S., and it has offices in 20 cities worldwide, with the most recent addition of Munich in 2016.
 It is a full-service law firm, with broad experience in transaction and litigation matters.
 Its original predecessor firm was founded in 1866 and had former first lady Mary Todd Lincoln, then the widow of President Abraham Lincoln, among its earliest clients.
 The firm was formed as the result of the merger of two firms: the Chicago-based Sidley & Austin, founded in 1866, and the New York-based Brown & Wood, founded in 1914.
 The merger was completed in May 2001.
 The firm's headquarters is at One South Dearborn in Chicago's Loop.
Christina M. "Tina" Tchen (, pinyin: Chén Yuǎnměi) (born January 25, 1956) is an American lawyer.
 From 2011 until 2017, she served as Assistant to President Barack Obama; Chief of Staff to First Lady Michelle Obama; and Executive Director of the White House Council on Women and Girls.
 From the date of Obama's inauguration until January 5, 2011, she was the Director of the White House Office of Public Engagement, previously known as the Office of Public Liaison.
Brown & Wood was a New York-based law firm established in 1914 that merged with Chicago-based Sidley & Austin in 2001 to form Sidley Austin Brown & Wood, later shortened to Sidley Austin.