[国外标准] DIN 562-1987 Square thon nuts Product grade B
[国外标准] SAE J740-1986 COUNTERSUNK SQUARE HOLES FOR CUTTING EDGES AND END BITS
[国外标准] JIS B1182-1995 Square head bolts
[国外标准] JIS B1163-2001 方螺母Square nuts
[国外标准] JIS B1118-1995 Square head set screws
[国外标准] ASTM F2062-00(R2006) Square drive interconnections on surgical instruments