At the end of the article you can click on three other articles she wrote on the think tank/lobbying connection, including one on think tank scholars and their lobbying ties.
Ms. Bennett is a co-founder of Muckety, a website that uses interactive maps to show relationships between people, businesses, and organizations. It has a "think tank" section which has some interesting maps, including this one titled "American Enterprise Institute: Safe House for Bush Alumni."
Also, here is a Salon article titled "How Bahrain Works Washington" written by Ken Silverstein that shows the importance of think tanks to lobbyists.
Now lobbyists (for foreign and domestic clients) seek to advance their clients’ interests in Washington through other means: making contributions to think tanks and universities; funding bilateral business associations that focus on trade issues while advocating, directly or indirectly, for enhanced political ties...As one Washington lobbyist told me, “Access lobbying is dead. Congress is gridlocked so meetings on the Hill are useless. Now it’s all about perception and molding public opinion. That’s why so many lobby firms have become integrated, and do so much work on the PR side.”