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³⁴ See ibid., 928–30, on this point.

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⁴⁶ Applying formula (3) we can calculate the effect of borders on trade as 100 * (1 − exp(−0.228) for state borders, and 100 * (1 − exp(−0.277) for external borders.

⁴⁷ The distance equivalent of the state border effect can be calculated as exp (−0.228/− 0.089).

⁴⁸ The distance equivalent of the external border effect can be calculated as exp (− 0.277/− 0.089).

⁴⁹ Wolf, “Was Germany Ever United?” Table 2.