In a comment I mentioned a book by its cover title name, "programming the Z80". That is also the title used on the inside front cover. However, both the spine of the book and back cover refer to it as "PROGRAMMING THE Z80". The copyright blurb was no help, not even mentioning the title at all:
Copyright © 1979 SYBEX Inc. World Rights reserved. No part of this publication may be ... without the prior written permission of the publisher.
Library of Congress Card Number: 78-73741
ISBN Number: 0-89588-013-X
Printed in the United States of America
Printing 10 9 8 7 6 5 4 3 2 1
The Library of Congress lists it as "Programming the Z80 / Rodnay Zaks". Searching the ISBN online, it seems to be the same, normal "title capitalization", although I found one reference where "The" was capitalized as well. Wiley, which now owns the SYBEX brand, does not list the book as part of their catalog nor even as part of their SYBEX subcatalog.
So in addition to whether capitalization matters technically, should we strive as a matter of respect to represent the name in the way the author wished it to be? It's not that Rodnay Zaks didn't have a choice; he apparently founded SYBEX and wrote several books in a "programming the ..." series.
This section was originally an off-topic aside. I converted it to an on-topic question in another SE: Why are Library of Congress searches treated as live sessions?