BIBLIOGRAPHY ABOUT BLACK DEATH

it's the deadliest disease that ever has been caused it killed 75 to 100 million people in Europe and north Africa from 1347 to 1351

loess contribute to the flooding of rivers by providing the silt that is washed into rivers and constantly raises the bed of the rivers. this elevation above the surrounding flood plains and dams allow the river to overwhelm the dams and flood thousand of square miles of neighboring flood plains.

answer; researchers typically cannot control people's sexual behaviors as would be necessary in an experiment;