Cross-references, abbreviated descriptions, external and internal links

The printed version of this catalogue employs a concise cross-referencing system to avoid or minimise repetitions of similar or identical material within the source descriptions for each work; one reason for this was to limit the volume to no more than 1,000 pages for practical reasons. As no such constraints exist in respect of the online version, we have retained this system only in the case of simple cross-references, the main purposes of which are outlined in the following indicative list:

The front pages of many wrappers/‌covers contain a more or less exact replica of an ITP, STP or ATP. Comments are provided either confirming that they are identical (e.g. 27–1c-BR, 45–1d-ME, 63–1-BR) or noting the differences be­tween them, which typically concern the decoration or ink colour (e.g. 8–1b-KI (D-LEm copy), 32/1–1-Sam, 32/1–1a-Sam (A-Wn copy)). Where a single catalogue entry contains several similar or identical wrappers, we provide cross-references to those elements that remain constant. Usually such references pertain to a similar copy within the same cata­logue entry (e.g. 34/3–1-B&H (PL-Wbfc second copy), 34/3–1f-B&H (US-NYp copy)), but in three cases they relate to the title page of another roughly contemporaneous impression (34/1–1a-B&H, 34/2–1-B&H (US-NYp copy), 59–1d-F).