# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/^\d+\s/''/gm;t' <<< "0 Ackman, R.G.. Tocher, C.S. and McLachlan. J.. 1968. Marine phytoplankter fatty acids. J. Fish. Res. Board Can., 25: 1603-1620. 1"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html