;Gravitational time dilation; time dilation in circular motion==External links==*Twin Paradox overview in the Usenet Physics FAQ*The twin paradox: Is the symmetry of time dilation paradoxical?
* Релятивистское замедление времени* Эксперимент Хафеле — Китинга* Twin Paradox overview in the Usenet Physics FAQ* Wolfgang Rindler,* FLASH Animations: "from John de Pillis.