أرسل هذا في رسالة قصيرة: The compound equation related to the Bessel-Helmholtz equation and the Bessel-Klein-Gordon equation

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