square head bolt

square head column stopper

allen head screw

button head screw

casing screw head

cheese head screw

countersunk head screw

fillister head screw

flat head screw

pan head screw

round head screw

socket head screw

square root sum of square method

hammer head [= hammer head shark]

head to head configuration

head to head structure

0-1 square matrix

1 square centimetre

1 square decimetre