Shiva Purana
स्त्रीपुंसयोर्विभूतिश्च स्त्रीपुंसाभ्यामधिष्ठितम् ॥ परमात्मा शिवः प्रोक्तश्शिवा सा च प्रकीर्तिता ॥ ३८ ॥
It is the effect of the superhuman power of male and female. It is presided over by a male and a female. Śiva is the great Ātman and Śivā the great Śakti.
english translation
strIpuMsayorvibhUtizca strIpuMsAbhyAmadhiSThitam ॥ paramAtmA zivaH proktazzivA sA ca prakIrtitA ॥ 38 ॥
hk transliteration by Sanscript