Shiva Purana
वासुदेवो ऽनिरुद्धश्च प्रद्युम्नश्च ततः परः ॥ संकर्षणस्समाख्याताश्चतस्रो मूर्तयो हरेः ॥ १३४ ॥
After him came Vāsudeva, Aniruddha and Pradyumna. Sankarshana is described as the four idols of Lord Hari.
english translation
vAsudevo 'niruddhazca pradyumnazca tataH paraH ॥ saMkarSaNassamAkhyAtAzcatasro mUrtayo hareH ॥ 134 ॥
hk transliteration by Sanscript