Rachel carson's book silent spring, published in the 1960s,

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.

the viking voyages took place during the middle ages, which was about this time. 500 to 1350. the viking voyages took place during the middle ages, which was about this time.