books.google.com - Since its original publication in 1940, this book has been revised and modernized several times, most notably in 1948 (second edition) and in 1967 (third edition). The material is organized into four main parts: general notions and concepts of lattice theory (Chapters I-V), universal algebra (Chapters...https://books.google.com/books/about/Lattice_Theory.html?id=0Y8d-MdtVwkC&q=open+sets&utm_source=gb-gplus-shareLattice Theory