Books about Triangles (Interpersonal relations) -- Fiction (sorted alphabetically)
- Portrait of a Lady — Volume 2 Henry James
- Potter and the Clay: A Romance of Today Maud Howard Peterson
- Prodigal Son Sir Hall Caine
- Professor Charlotte Brontë
- Proud Lady Neith Boyce
- Quill's Window George Barr McCutcheon
- Radio mates Benjamin Witwer
- rat-trap Dolf Wyllarde
- Real Charlotte E. Oe. Somerville and Martin Ross
- Rich Man, Poor Man Maximilian Foster
- Robert Kimberly Frank H. Spearman
- Rodmoor: A Romance John Cowper Powys
- Romance of Zion Chapel [3d ed.] Richard Le Gallienne
- Root of Evil Jr. Thomas Dixon
- Scarlet Letter Nathaniel Hawthorne
- Scarlet Letter Nathaniel Hawthorne
- Shadow of the Past F. E. Mills Young
- Sininen silmäpari (Finnish) Thomas Hardy
- Sister of the Red Cross: A Tale of the South African War L. T. Meade
- Sleeping Fires: a Novel Gertrude Franklin Horn Atherton
- Soldiers of Fortune Richard Harding Davis
- Sons of the Morning Eden Phillpotts
- Sous la neige (French) Edith Wharton
- Star of India Alice Perrin
- Stella Fregelius: A Tale of Three Destinies H. Rider Haggard