Astanga Hrudaya
एकादशी च, युग्मासु स्यात्पुत्रोऽन्यासु कन्यका। उपाध्यायोऽथ पुत्रीयं कुर्वीत विधिवद्विधिम्॥२७॥
the first three days of it are insuspicious, so also the eleventh day, copulation on even days leads to birth of a son and on other (odd) days to a daughter The priest should perform the ritual of begetting a son, in accordance with the prescribed procedure (for persons of upper castes) and for sudras (persons of lower castes) by making them bow to Gods, without uttering sacred hymns;
english translation
ekAdazI ca, yugmAsu syAtputro'nyAsu kanyakA। upAdhyAyo'tha putrIyaM kurvIta vidhivadvidhim॥27॥
hk transliteration by Sanscript