"Ryff, Petrus"@en . "1629Z"^^ . . . . "Petrus Ryff (or Ryffius) (Basel German pronunciation: [rif]; May 8, 1552 \u2013 May 19, 1629) was a Swiss mathematician, physician and chronicler from Basel."@en . "Petrus Ryff"@en . . "1552-05-08Z"^^ . "1629-05-19Z"^^ . . . "Swiss scientist" . . "1552Z"^^ .