Burkhardt, F.; Secord, J.A.; Dean, S.A.; Evans, S.A.; Innes, S.; Pearn, A.M. 2008. The correspondence of Charles Darwin: January – June 1868. Cambridge, Cambridge University Press. vol. 16 (parts 1-2), pp. i-xlvi, 1-604, i-iv, 605-1252. { copied = true; setTimeout(() => copied = false, 10000); }).catch(err => { console.error('Failed to copy:', err); }); " type="button" :class="copied ? 'bg-secondary border-secondary' : 'border-primary hover:bg-primary'" class="group lg:min-w-64 flex items-center justify-between gap-5 border border-solid px-5 py-2 cursor-pointer transition-colors"> PDF download available