Bibliography 

• http://samadhi.jpl.nasa.gov/msl/quicklook/gravpbql.html

 
• http://nap.edu/html/gpb

 
• http://einstein.stanford.edu/highlights/hl.html

 
• http://news.bbc.co.uk/1/hi/sci/tech/3640901.stm

 
• http://www.nasa.gov/centers/marshall/news/release...