This series includes Landauer's various efforts to keep records of her growing collection. She grouped and listed items by their physical location, by type of media, or by subject. This series is composed of three subseries: Bound catalogs, Card catalogs, and Notebook catalogs.

Series II includes only correspondence received by Bella C. Landauer. In general, her outgoing correspondence does not seem to have been kept. Landauer did not keep files on correspondents, but instead pasted her correspondence into large scrapbook albums, as she did her ephemera collections. Two of these scrapbooks are part of this series. This series also includes three smaller bound volumes in which correspondence, mainly about specific aspects of Landauer's collections, has been bound together or pasted onto bound pages. The volume with a cover title "Scraps - Bella C. Landauer" contains correspondence, mainly about aeronautics and aeronautical ephemera, from 1930 to 1936. Some of these letters are in French from French correspondents. The volume with spine title, "G and S correspondence Reginald Allen" holds correspondence as well as ephemera relating to Reginald Allen and Gilbert and Sullivan. Allen was an arts administrator and a collector of Gilbert and Sullivan ephemera. The correspondence covers the period between 1939-1951 and is mainly related to discussions of Gilbert and Sullivan ephemeral finds. Some fragile material was removed from the title page of this volume and foldered at the time of processing. A third volume with "B. C. L." embossed on the cover is titled "Letters from composers of Walt Whitman Music 1936-1937." It has a photograph of Walt Whitman pasted on the inside cover. Most of the letters are related to the publication of Landauer's book, Leaves of Music by Walt Whitman, from the Collection of Bella C. Landauer (1937), a listing of sheet music related to Whitman or including Whitman verses.

Landauer did not always segregate or bind her correspondence; much of it can be found scattered throughout the collection scrapbooks, especially when the letter or postcard related to one specific item of ephemera. This aspect makes it difficult to acquire a complete sense of the volume of correspondence she encountered. In general, Landauer did not broadly solicit donations to her collections, preferring to negotiate with her trusted dealers. During World War II, however, she does appear to have sent out letters to a variety of companies that were awarded the Army-Navy "E" Award for high achievement in war production. Landauer requested copies of the companies' award ceremonies programs; several folders of unbound correspondence are replies to her inquiries, sometimes with the award programs enclosed. One folder of miscellaneous letters includes other loose correspondence to Landauer. Unused sheets of Landauer's letterhead and one small spiral notebook of addresses are included in this series.

Series III includes many of Bella C. Landauer's published books, articles, and compilations of items culled from her collections. Many of these same publications (as well as others not included here) can also be found in the New-York Historical Society library. Most of the copies found in this collection are extra-illustrated or have notations in Landauer's hand. The series is divided into three subseries: Articles; Monographs; and Compilations. These publications have been individually cataloged into the New-York Historical Society library catalog and can also be accessed through that resource. Thus they are merely listed here, and are not extensively described.

Series IV contains eight bound scrapbooks, in which primary materials are pasted onto pages or were bound as pages themselves into pamphlet binders. Several of these books were bound with embossed titles on their covers, but none have a title page, and they were not published.

"Advertisements" contains pages from a commercial directory that are randomly bound into a volume. The businesses shown are from New York City and from New England and Boston. Page numbers are random and often repeated, leading to the conclusion that these were removed from separate directories and bound together. Many businesses shown seem to have some connection to printing concerns: engravers, bookbinders, etc. The advertisements are mainly from 1855 and 1856.

"Aviation University Club exhibition," consists of 11 8 x 10 inch black and white exhibit photographs of some of Landauer's aeronautical collection which was on display at the University Club in New York in 1942. Photographs are individually bound into a pamphlet binding. The scrapbook includes a letter from the editor of Aviation magazine explaining the provenance of the photos, which were given to Landauer by that publication. This scrapbook was disbound and foldered at the time of processing.

"Old New York" contains forty engravings, lithographs, and chromolithographs of New York scenes, especially downtown buildings and views. The majority of prints are individually bound together into a book with an embossed title. Most were contemporary views printed for D. T. Valentine's Manual between 1858 and 1864, and were lithographed by Major and Knapp; A. Weingartner; Sarony, Major and Knapp; Geo. Hayward; or A. Brown and Co. Scenes include Five Points intersections, uptown intersections (Broadway and 8th Avenue, for example), High Bridge, Central Park, the U.S. Iron Clad Steam-Ship "Roanoke," and Washington Market. Other prints not made for Valentine's are of the American Museum and harbor scenes. Three prints are for Jos. Shannon's Manual, 1863-1868, and were lithographed by W. C. Rogers and Co.

"Views of Old N.Y." includes sixty prints, which are also individually bound together. This volume includes many plates from books. Prints are either engraved or lithographed, and some are hand colored. The views in this scrapbook are earlier than those found in the previous scrapbook. Many have titles like "New York in 1776" and "Brooklyn (in the olden time)." Other views include the Crystal Palace, City Hall, and a plate that shows a map of the harbor titled "Plan de la Baie de New-York." This scrapbook also includes the front cover, with a photo of the Woolworth Building, of "Men of New York," a September 1925 YMCA periodical.

"War Songsters" is a small 5 x 8 inch volume holding 55 song lyrics to war songs, most printed on sheets of notepaper with an engraved view at the top. Most songs were lithographed by Charles Magnus, and come from his "500 Illustrated Ballads" series. Several of these sheets are hand colored. Most songs date from the Civil War, although earlier patriotic songs are also included. "The Star Spangled Banner" is present as well as "Sherman's March to the Sea," and "The Soldier's Dream." A few ephemeral pieces are pasted into the front cover.

"Washington" is a scrapbook containing ephemeral items with images of or relating to George Washington. It includes many engraved portraits and prints from Washington's life, as well as his image on postage stamps, trade cards, and product wrappers.

There is also an untitled scrapbook is untitled that contains ephemera relating to George Washington. Items include needlepointed slogans, postcards, matchbooks, bookmarks, and programs.

"George Washington" is a bound scrapbook with an embossed title. In addition to the ephemera items described above, it inccludes a lottery ticket with a presidential signature.

Scrapbooks are arranged alphabetically.

Series V contains Landauer's collection of published works by others, used as reference volumes in her Collection Room at the New-York Historical Society. They include monographs, pamphlets, and issues of journals. The majority of the nineteen volumes are extra-illustrated. Landauer sometimes bound items from her collection or correspondence with the author into these volumes (many of which she had bound by the New-York Historical Society or enclosed in cardboard binders.) Extra-illustration often includes items that are related to the author of the books or the subject of the books. Two issues of the Bodleian Library Record include articles about John Johnson, whose large collection of ephemera at Oxford interested and inspired Landauer. A catalog from an exhibition of the John Johnson collection is also included. A typescript list entitled "The Sanctuary of Printing" was sent to Landauer from Johnson. The list seems to be his cataloging system for his ephemera collection. George Phillips' England's Climbing-Boys; a History of the Long Struggle to Abolish Child Labor in Chimney-sweeping, is bound in a volume with several pamphlets about chimney-sweeps, and is extra-illustrated with scraps in the shape of chimney-sweeps, postcards, clippings, and other ephemera bound in. Also includes correspondence, including a valentine from Phillips to Landauer. Most pamphlets were originally housed in pamphlet binders, and were removed from these at the time of processing. Two auction catalogs from Landauer's sales at the Anderson Galleries are treated as monographs.

The series is divided into two subseries: Journals and Monographs.

Series VI is a bound volume that contains correspondence and business records relating to Aerial Advertising Inc, a New York City organization that flew airplanes with advertising slogans and messages spelled out in lights on its bottom so as to be seen from below. "The Flying Electric Sign" was its slogan. These records cover the period from 1928 to 1931. Colonel Thatcher T. P. Luquer was a stockholder in and board member of Aerial Advertising Inc., and was the compiler of these records. Correspondence includes letters to Luquer from the president of Aerial Advertising, C. Gilbert Peterson, about the business's prospects, as well as company balance sheets and investment appeals. The volume also includes an Aerial Advertising descriptive catalog 1928. The corporation was dissolved due to bankruptcy in January 1931.