Dhaka, July 19 -- A mother and her nine-year-old son lost in the rocky mountain forest of Sierra Nevada in the US state of California were rescued thanks to a trail of handwritten notes they left behind - after getting stranded for more than 24 hours.A search and rescue team found the pair on 12 July after discovering multiple notes tucked beneath rocks, left by the mother, aged 49. "HELP. Me and my son are stranded with no service and can't call 911," one said. The pair were found by members of the Calaveras County Volunteer Search and Rescue Team, who already happened to be in the area.The mother told ABC10 it had been a "very scary experience", but paid tribute to the "amazing" efforts of the rescuers. The mission was detailed in a Fac...