2024 A collection of variations on principal themes. Albert Einstein 2024 Bib @book{opus_1, title = {A collection of variations on principal themes.}, author = {Einstein, Albert}, year = {2024}, publisher = {Courier Corporation}, } 2014 op_1_no_1 Opus 1 No 1 He. M , SurreyOp. 1 No. 1 (C major) is written in 2014. , May 2014 Abs HTML PDF s.