APA (7th ed.) Citation

Allingham, H. P., Allingham, W., & Williams, E. B. (1911). Letters to William Allingham. Longmans, Green and Co..

Chicago Style (17th ed.) Citation

Allingham, Helen Paterson, William Allingham, and E. Baumer Williams. Letters to William Allingham. London ; New York: Longmans, Green and Co., 1911.

MLA (9th ed.) Citation

Allingham, Helen Paterson, et al. Letters to William Allingham. Longmans, Green and Co., 1911.