1979, G. L. Weissler and Robert Warner Carlson, Vacuum Physics and Technology Chapter 5, Titanium has become the preferred getter for general vacuum-pumping applications because of its relatively high vapor pressure characteristic and its broad spectrum chemical reactivity.
2003, John F. O'Hanlon, A Users Guide to Vacuum Technology Chapter 14, Many reactive metals rapidly pump large quantities of active gases because they getter (react with) the gases.