What does this mean??!!

Hello everyone, I am new to this site and am pretty excited on all the things I will learn by talking to everyone. I would like to start my adventure with a saying I found in the from of a book that I am researching.... The book is "The Adventures of Tom Sawyer", Mark Twain... on the copyright page is has the paragraph stating... "This book, while produced under wartime conditions, in full compliance with government regulations for the conservation of paper and other essential materials, is complete and unabridged.".... And i am also confused on the print date of this particular copy I have.... below is what is says exactly....

HARPER & BROTHERS, NEW YORK
ESTABLISHED 1817
THE ADVENTURES OF TOM SAWYER
Copyright, 1871, 1899, and 1903, by Samuel l. Clemens
Copyright, 1917, by Clara Gabrilowitsch
Copyright, 1917, 1920, by Mark Twain Company
Copyright, 1922, by Mark Twain Company
Printed in the United States of America

Can someone help me please?
Thanks

I believe that the book was being printed during World War I, which is why it says it follows regulation for the conservation of paper. Certain goods would be in higher demand and thus more scarce during periods of war.

The book is complete and unabridged, which means that it should contain the whole text, with no missing or shortened parts.

The print date for your particular copy of the book appears to be 1922 since it is the last date listed.

Which shows that certain materials were in short supply for sometime after the war.

The Mark Twain Company! Truly Corporate American