There are 2 studies that match your criteria.
Criteria: Study Type=In Vivo,Freq Range=300 Hz - 300 kHz (Intermediate),Study Subtype=Long Term Animal Bioassay

View This Study - Citation No: 4390
Title	LONG-TERM EXPOSURE OF SPRAGUE DAWLEY RATS TO 20 KHZ TRIANGULAR MAGNETIC FIELDS
Reference	Int J Radiat Biol, Vol. 82, Pg. 285 - 291, 2006
Author(s)	Lee H. J., Kim S. H., Pack J. K., Choi H. D., Lee Y. S., et al .
PubMed UID	16690596
Project ID	2009
View This Study - Citation No: 4391
Title	TOXICITY BIOASSAY IN SPRAGUE-DAWLEY RATS EXPOSED TO 20 KHZ TRIANGULAR MAGNETIC FIELD FOR 90 DAYS
Reference	Bioelectromagnetics, Vol. 27, Pg. 105 - 111, 2006
Author(s)	Kim S. H., Lee H. J., Choi S. Y., Pack J. K., Lee Y. S., et al .
PubMed UID	16283665
Project ID	2009