This was ordered as a reference volume. Lemprière is a standard dictionary of the Classical world, but because of its age often cites ancient / authors & references as opposed to secondary or later scholarship.
To quote from the Wiki, "The Bibliotheca Classica' (Reading, November, 1788), or 'Classical Dictionary containing a full Account of all the Proper Names mentioned in Ancient Authors,' is the best-known work of John Lemprière, an English classical scholar. Edited by various later scholars, the dictionary long remained a readable if not absolutely trustworthy reference book in mythology and classical history. Lemprière wished "to give the most accurate and satisfactory account of all the proper names which occur in reading the Classics, and by a judicious collection of anecdotes and historical facts to draw a picture of ancient times, not less instructive than entertaining." [...]
Which says it all, really!
It is not 100% trustworthy, as pointed out. Nor is it a substitute for the huge magisterial Oxford Classical Dictionary, but for quick look-ups Lemprière's pounds lighter than the OCD, weight-wise.