Describir: Problems of the 19th and 20 th centuries /

 _    _     ______              _____     ______     ___              
| \  / ||  /_   _//     ___    |  ___||  /_   _//   / _ \\    ____    
|  \/  ||   -| ||-     /   ||  | ||__      | ||    | / \ ||  |    \\  
| .  . ||   _| ||_    | [] ||  | ||__     _| ||    | \_/ ||  | [] ||  
|_|\/|_||  /_____//    \__ ||  |_____||  /__//      \___//   |  __//  
`-`  `-`   `-----`      -|_||  `-----`   `--`       `---`    |_|`-`   
                         `-`                                 `-`      
 __   __  
 \ \\/ // 
  \ ` //  
   | ||   
   |_||   
   `-`'