فهرست نشریات علمی دسترسی آزاد ایران

It is a great honor for me to write a few introductory words to the present volume of CGASA  dedicated to Professor George A. Grätzer. The occasion for  this dedication  is that we are celebrating two anniversaries  in 2018 related to him.  Namely,  (A1) it was 55 years ago that the Grätzer--Schmidt Theorem was published, and (A2) it was 40 years ago that  G. Grätzer's  General Lattice Theory, which immediately became the Book in  lattice theory for decades,  appeared.