Note 6 - Inventories
 6 Months Ended
Sep. 30, 2017
Notes to Financial Statements  
Inventory Disclosure [Text Block]
NOTE
6.
INVENTORIES

     Inventories are shown in the following table:
 
   
September
30,
2017
    
March 31,
2017
  
Raw materials
   $
790,901
     $
786,775
  
Work in process
    
2,007,545
      
1,968,990
  
Finished goods
    
706,032
      
602,533
  
Total inventories
   $
3,504,478
     $
3,358,298