Robert Hume, Chandogya Upanishad, The Thirteen Principal Upanishads, Oxford University Press, pages 261-262
Original Sanskrit: Samkhya karika Compiled and indexed by Ferenc Ruzsa (2015), Sanskrit Documents Archives; Second Translation (Verse 1): Ferenc Ruzsa (1997), The triple suffering - A note on the Samkhya karika, Xth World Sanskrit Conference: Bangalore, University of Hungary, Budapest; Third Translation (all Verses): Samkhyakarika of Iswara Krishna John Davis (Translator), Trubner, London, University of Toronto Archives
Harvey (2013, p. 30): ""suffering" is an appropriate translation only in a general, inexact sense [...] In the passage on the first True Reality, dukkha in "birth is dukkha" is an adjective [...] The best translation here is by the English adjective "painful," which can apply to a range of things." Harvey, Peter (2013). The Selfless Mind: Personality, Consciousness and Nirvana in Early Buddhism. Routledge. ISBN978-1-136-78336-4.
Original Sanskrit: Samkhya karika Compiled and indexed by Ferenc Ruzsa (2015), Sanskrit Documents Archives; Second Translation (Verse 1): Ferenc Ruzsa (1997), The triple suffering - A note on the Samkhya karika, Xth World Sanskrit Conference: Bangalore, University of Hungary, Budapest; Third Translation (all Verses): Samkhyakarika of Iswara Krishna John Davis (Translator), Trubner, London, University of Toronto Archives
Brihadaranyaka Upanishad, Retrieved 16 May 2016 from "SanskritDocuments.Org" at Brihadaranyaka IV.iv.14, Original: इहैव सन्तोऽथ विद्मस्तद्वयं विद्मस् तद् वयम्न चेदवेदिर्महती विनष्टिः । ये तद्विदुरमृतास्ते भवन्त्य् अथेतरे दुःखमेवापियन्ति ॥ १४ ॥
Monier-Williams 1899, p. 483, entry note: : "according to grammarians properly written dush-kha and said to be from duḥ- and kha [cf. su-khá]; but more probably a Prākritized form for duḥ-sthā, q.v."Monier-Williams, Monier (1899), A Sanskrit-English Dictionary(PDF), London: Oxford University Press