Fingerprints; invisible ink; writing on one skin; x-rays.
Is There a Place in Time When One Would Be Allowed to Carry Home a Tallis From Shul?;
How to Work with the Light in the Refrigerator on Shabbos. Part 2;
Putting Away Laundry That Is Still Hanging Around From Before Shabbos. Taking Out Frozen Milk or Frozen Challah for After Shabbos;