Elastic constants (E, G & K)

If you are studying the structural engineering then there are these three elastic constants which you have to use in various theories.
(1)Young's modulus of elasticity E
(2) Modulus of rigidity G
(3) Bulk modules  K
E is the elastic constant which is defined as the linear stress over linear strain.
G is defined as the shear stress over shear strain.
K Bulk modulus is defined as the stress over volumetric strain.
Poison's ratio is another constant which is defined as the lateral strain over linear strain.(n)
Numerically E= 3k(1-2n)
                 also E=2G(1+n)