Guyana's history has been substantially shaped by immigration, and writings often address the topics of slavery and indenture, as well as reflecting the culture of the various immigrant groups. One of the earliest and most notable Guyanese authors was Edgar Mittelholzer, author of "Corentyne Thunder" (1941). His works often deal with issues of interracial relations, particularly the strain between European and non-European Guyanese. Kyk-Over-Al literary journal, published in 1945 and edited by A. J. Seymour, collected poetry and other works from Guyana and the West Indies. A major contributor, Martin Carter, is considered Guyana's greatest poet. Mid 20th century, poetry served as a medium to express the Guyanese identity, in light of independence from British colonial rule and creating a style unique to the country.