الوصول الحر: https://www.jstor.org/stable/2241809Test
الوصول الحر: https://www.jstor.org/stable/2241707Test
الوصول الحر: https://www.jstor.org/stable/3035560Test
الوصول الحر: https://www.jstor.org/stable/2241359Test
الإتاحة: https://doi.org/10.1214/aos/1176350486Testhttp://projecteuclid.org/euclid.aos/1176350486Test