Bind them the best suitable way
Plastic Binding
Plastic Binding

A4/A3 binding available

Wire Binding
Wire Binding

A4/A3 binding available

square fold stapled
square fold stapled
Perfect Binding
Perfect Binding
Thermal Binding
Thermal Binding

Available for A4

Saddle-stitch Staple
Saddle-stitch Staple

Available for most sizes