History 28 Biological invasions 12 Politics and government 9 Invasive species 6 Iraq 6 Weeds 5 Biodiversity conservation 4 Cancer 4 Cancer cells 4 India 4 Invasive plants 4 World War, 1939-1945 4 Agronomy 3 Dissertations, Academic (Ph.D) 3 Ecology 3 Foreign relations 3 Genetic aspects 3 Human sacrifice 3 Indo-Europeans 3 Invasion 3 Invasions 3 Kandh (Indic people) 3 Kuwait 3 Marine ecology 3 Medieval Indian history--Akbar--Mughals 3 Molecular aspects 3 Plant Ecology 3 Population 3 Psychology 3 Social conditions 3