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

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