h6_19740207.pdf
h6_19740221.pdf
h6_19740530.pdf
h6_19740606.pdf
h6_19740718.pdf
h6_19740725.pdf
h6_19740815.pdf
h6_19740912.pdf
h6_19740919.pdf
h6_19750220_revision.pdf
h6_19750320.pdf
h6_19740627.pdf