Consolidated Condensed Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Oct. 31, 2018		Apr. 30, 2018
Short term investments	$ 3,726		$ 4,982
Allowance for doubtful accounts	$ 17		$ 14
Common stock, par value (in dollars per share)	$ 0.10		$ 0.10
Common stock, shares authorized (in shares)	30,000,000		30,000,000
Common stock, shares issued (in shares)	10,000,000		10,000,000
Treasury stock, shares (in shares)	310,666	[1],[2]	308,380	[3]

[1] Includes 207,047 shares with a total average cost of $2,792,000 that were acquired during the $3 million repurchase program which was authorized in September 2012 and expired in October 2019.

[2] On October 19, 2018, the Companys Board of Directors authorized the repurchases up to $2,000,000 of shares of the Companys common stock of which none were purchased through October 31, 2018.

[3] Includes 85,219 shares with a total average cost of $1,036,000 that were acquired during the former repurchase program which was authorized in January 2011 and expired in January 2012; 18,400 shares were acquired prior to January 2011.