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Robertson, F. W. In Memoriam. 
Dawson, Dr. S. E. Study of the Princess, annotated. 
Genung, J. F. In Memoriam, its Purpose and Structure. 
Woodberry, G. E. The Princess, with Notes and Introduction. 
Farrand, Wilson.  The Princess, with Notes and Introduction. 
Gatty, Alfred.  Key to In Memoriam. 
Harrison, Frederic.  Tennyson, Ruskin, and Mill.