column
![](/style/images/custom/toleft.png)
![](/style/images/custom/toright.png)
1988, 9(3): 225-229.
1988, 9(3): 230-238.
1988, 9(3): 255-261.
1988, 9(3): 277-283.
1988, 9(3): 317-320.