Shiva Purana
यमश्च यमुना चैव यमलौ संबभूवतुः ॥ एवं हि त्रीण्यपत्यानि तस्यां जातानि सूर्य्यतः ॥ ५ ॥
Yama and Yamuna became the two Yamalas. Thus she had three children born to her from the sun.
english translation
yamazca yamunA caiva yamalau saMbabhUvatuH ॥ evaM hi trINyapatyAni tasyAM jAtAni sUryyataH ॥ 5 ॥
hk transliteration by Sanscript