MB3 103b: Secular Reading on Shabbos (307:16-19)

Reading secular material on Shabbos is problematic on Shabbos. Reading biographies of gedolim on Shabbos. Reading secular material written in Hebrew. Playing chess on Shabbos. Reading cookbooks or professional journals on Shabbos. Learning secular subjects on Shabbos.

Protecting merchandise that may be ruined on Shabbos (e.g. by water).