“… Source: The authors. Notes: P1, Akintaro (2016): P2, Dauda (2015): P3, Shanaei and Tahsildari (2015): P4, Neupane (2014): P5, Tinuke (2014): P6, Wadongo (2014): P7, Ashraf and Khan (2013): P8, Eydii (2013): P9, Trierweiller et al (2012): P10, Malik et al (2011); P11, Zheng, Yang, and McLean (2010): P12: Kontoghiorghes and Frangou (2009): P13, U. Dhar and Dhar (2009): P14, Vinitwatanakhun (2002): P15, Fichman (2001): P16, Pounder (1999): P17, Kleeman and Richardson (1985): P18, Antia and Cuthbert (1976): P19, Connolly et al (1980). …”