BibTeX does not have the right entry for preprints. This is a hack for producing the correct reference:
@booklet{EasyChair:3660,
author = {Takayuki Kobayashi},
title = {1⁄f Fluctuations on a Chain of Causal Relationships},
howpublished = {EasyChair Preprint 3660},
year = {EasyChair, 2020}}