The New York Public Library has a couple divisions that hold Sylvia Plath manuscripts and related materials. In the Manuscripts and Archives division is The New Yorker records, which holds correspondence to, from, and about Plath. The Berg Collection holds a varied assortment of Plath materials, from juvenilia to late works. This post will merely summarize the holdings, and but to learn more, either visit the library yourself (recommended) or please see " These Ghostly Archives 4: Looking for New England " by Gail Crowther and myself, published in Plath Profiles 5 (Summer 2012) (also recommended). New Yorker Records The bulk of material on Plath is in Series III, Editorial Correspondence, subseries 3.3 Fiction Correspondence, 1952-1980, for the following years; 1958, 1959, 1960, 1961, 1962, 1963, 1970, 1971, 1973, 1977. In the scope and content note, it explains that poetry correspondence is included in the fiction correspondence file. There are also some Plath related ...
Sylvia Plath Info Blog by Peter K. Steinberg. The blog of A celebration, this is.