Jelaskan Sumber primer dari Sidney Webb, 1st Baron Passfield

Mackenzie, Norman, ed. The Letters of Sidney and Beatrice Webb (3 volumes. Cambridge University Press, 1978, pp. xvii, 453; xi, 405; ix, 482)

Volume 1. Apprenticeships 1873–1892 (1978)

Volume 2. Partnership 1892–1912 (1978)

Volume 3. Pilgrimage, 1912–1947 (1978)