"The First World War Poetry Digital Archive is an online repository of over 7000 items of text, images, audio, and video for teaching, learning, and research. The heart of the archive consists of collections of highly valued primary material from major poets of the period. This is supplemented by a comprehensive range of multimedia artefacts from the Imperial War Museum."
1b) Magill On Literature / Literature Resource Center
One person will find a secondary source of information on the poem using an academic database such as MagillOnLiterature or Literature Resource Center.