The book is available at Hathi Trust (I have not checked for other online sources).
Table of Contents
I. Danish, Scandinavian, and German popular tradition; Extent of the thunderstone-belief in Europe and other continents
II. The thunderstone in pagan religions of the present day
III. The thunderstone in ancient Greece
IV. The thunderstone in ancient Italian religion and folklore
V. The original form and age of the ideas
VI. The classical Greek and the Tibetan thunderweapon
VII. The trident: the Greek triaina and the Indian Trisula
VIII. Mjolnir
IX. Retrospect
X. Sources and particulars
Denmark
Sweden
Norway
Iceland
Germany
Other European countries
Other continents
Some references
