Nucleic Acids Res. 2019 May 22. pii: gkz435. doi:10.1093/nar/gkz435

Miura F, Shibata Y, Miura M, Sangatsuda Y, Hisano O, Araki H, Ito T.

Highly efficient single-stranded DNA ligation technique improves low-input whole-genome bisulfite sequencing by post-bisulfite adaptor tagging.

Add a A-tail with TdT before ligation, because ligase prefers As.