In order to gain social worker certification and become eligible to work in the field, individuals must earn at least a Bachelor of Science or Bachelor of Arts. A master's degree in social work is usually required for state licensure as a clinical social worker. Some programs offer training in specialized fields.
View full size image. Johannes Gutenberg is usually cited as the inventor of the printing press. Indeed, the German goldsmith's 15th-century contribution to the technology was revolutionary â enabling the mass production of books and the rapid dissemination of knowledge throughout Europe.efore the invention of the printing press â sometime between 1440 and 1450 â most European texts were printed using xylography, a form of woodblock printing similar to the Chinese method used to print The Diamond Sutra in 868.
German printer who was the first in Europe to print using movable type and the first to use a press (1400-1468); His invention helped to spread Martin Luther's 95 Theses and the Protestant Reformation.