1. The simple pendulum with uniformly changing string length;Brearly,1966
2. The terminal behaviour of a uniformly shortening pendulum;Brearly;J. Aust. math. Soc.,1969
3. Advanced Dynamics;Timoshenko,1948
4. The lengthening pendulum;Werner;J. Aust. math. Soc.,1969
5. Vibration Problems in Engmeering;Timoshenko,1955