Valmiki Ramayana 5.37.8

वर्तते दशमो मासो द्वौ तु शेषौ प्लवङ्गम ।रावणेन नृशंसेन समयो यः कृतो मम॥

vartate daśamo māso dvau tu śeṣau plavaṅgama |rāvaṇena nṛśaṃsena samayo yaḥ kṛto mama ||

Our plain-language meaning of this verse is waiting for scholar review.