Melatonin and photorefractoriness: loss of response to the melatonin signal leads to seasonal reproductive transitions in the ewe.
Karsch FJ, Bittman EL, Robinson JE, Yellon SM, Wayne NL, Olster DH, Kaynard AH. Melatonin and photorefractoriness: loss of response to the melatonin signal leads to seasonal reproductive transitions in the ewe. Biol Reprod. 1986 Mar; 34(2):265-74.