@book { NgwaHistory,
    title = "Ngwa History",
    subtitle = "A Study of Social and Economic Changes in Igbo Mini-States in Time Perspective",
    author = "John Nwachimereze {Oriji}",
    year = "1991",
    publisher = "Peter Lang Verlag",
    address = "New York, United States of America",
    url = "https://www.peterlang.com/document/1082096"
}