The correspondence is arranged alphabetically by correspondent. Correspondence with journals is, however, listed according to the title of the journal. An asterisk * denotes that the folder contains more than 10 letters. Private correspondence is in boxes 43 and 44 (F L0005). Letters of recommendation and evaluations of other researchers are deposited as restricted material. Onsager also filed correspondence according to the topic. Thus Section II, Research material, contains numerous letters, in particular many from W.H. Furry (folder 9:81) and B. Kaufman (folders 9:95-9:96).