Note 6 - Inventories (Tables)
 3 Months Ended
Jun. 30, 2021
Notes Tables  
Schedule of Inventory, Current [Table Text Block]
  

June 30,
2021

  

March 31,
2021

 

Raw materials

 $696,047  $660,678 

Work in process

  2,399,064   2,220,723 

Finished goods

  574,915   1,019,376 

Total inventories

 $3,670,026  $3,900,777