Richard III (play) "Hamlet" is shorter than its Quarto counterpart. The play is often abridged; for example, certain peripheral characters are removed entirely. In such instances, extra lines are often invented or added from elsewhere in the sequence to establish the nature of characters' relationships. A further reason for abridgment is that Shakespeare assumed that his audiences would be familiar with his "Henry VI" plays and frequently made indirect references to events in them, such as Richard's murder of Henry VI or the defeat of Henry's wife, Margaret. "House of York" "House of Lancaster" "Woodville family" "Richard III's group" "Earl of Richmond's group"
Asimov's Guide to Shakespeare for doing this. Within each category, the plays are arranged according to internal (historical) chronology, making allowance for the several not based on actual events. Asimov notes how much is real history, and describes who the historical people were, where applicable. He traces those characters who appear in more than one play, and provides maps to explain key geographical elements. Asimov's approach is not popular with some readers' prejudices: "Asimov's Guide to Shakespeare", vols I and II (1970), . Gramercy Books. Nearly 800 pages long plus an index, the work was originally published in two volumes; Greek, Roman and Italian