Natyashastra
नेपथ्यगृहकं चैव ततः कार्यं प्रयत्नतः । द्वारं चैकं भवेत्तत्र रङ्गपीठप्रवेशनम् ॥ ९६॥
Next, the construction of the backstage should be carried out with effort. There should be one door for the entrance to the stage area.
english translation
nepathyagRhakaM caiva tataH kAryaM prayatnataH । dvAraM caikaM bhavettatra raGgapIThapravezanam ॥ 96॥
hk transliteration by Sanscript