Thread:Comments:Scientists say the moon is slowly shrinking/Comments from feedback form - "So it may be shrinking. Its ma..."/reply (6)

Please recommend a textbook reference for the proposition that field strength of a fixed mass at a fixed distance from the center increases with density.

As a counterexample, I have a copy of Stephen Eales' Planets and Planetary Systems to hand. Eales quotes the high school equation for Newton's law of universal gravitation without qualification, which I read as force per unit mass (outside the object) is proportional to mass divided by the square of the distance from the centre of mass. (ISBN 9780470016930, Wiley-Blackwell 2009, p.106)