1. R. Ekman arXiv:1906.04731 [physics.class-ph]
2. K.T. McDonald, Am. J. Phys. 59, 813 (1991)
3. The analysis by McDonald [2] has been further enlarged by the author himself and his collaborators along the years (during which the leaky tank car problem has also been introduced in general physics courses), given its didactic relevance. See the update version at that author website http://kirkmcd.princeton.edu/examples/tankcar.pdf as well as further generalizations at http://kirkmcd.princeton.edu/examples/rolling_pipe.pdf
4. See, for example, the lengthy discussions at: https://physics.stackexchange.com/questions/1683/mechanics-around-a-rail-tank-wagonhttps://www.physicsforums.com/threads/leaking-tank-wagon-very-hard-problem.455191/https://www.reddit.com/r/AskPhysics/comments/kv9ewr/a_railroad_tank_car_contains_milk_and_rolls_at_a/