[1] M.Hanna，Sightseeing in the UK，London：BTA/ETB Research Services，1996，pp.25，42.A similar number of hands-on attractions reached maximum capacity in 1992.M.Hanna，Sightseeing in the UK，London：BTA/ETB Research Services，1993，pp.24，41-2.
[2] Office of Population，Census and Surveys，Day Visits in Great Britain 1991/2，London：HMSO，1992.
[3] D.Maister，‘The psychology of waiting lines’，in C.H.Lovelock，Managing Services，Marketing Operations and Human Resources，New Jersey：Prentice Hall，1988，pp.176-84.