https://calhoun.nps.edu/handle/10945/929

http://www.geocities.ws/georgipolitov/index-2.html

It is very difficult to break 16th century scholastic dogma, e.g. imaginary numbers, used in taking the square root of negative numbers. If we are consistent, we should accept to take square roots only from positive numbers. The result of multiplication of the same numbers is always a positive number. If we take the square root of a negative number, we should place the negative sign before the radical sign/radix -√.