In 1879 he released the travel guide Reisehaandbog over Norge, popularly called Yngvar, which appeared in 12 editions until 1915 and came to play an important role in the spread of tourism. His guide books were published in English and German.
The Norwegian travel expert released his influential guidebook, Yngvar, in 1879, which went through 12 revisions until 1915 and contributed to the growth of tourism. His publications were translated into English and German.