The Journal of Economic Literature codes classification system (JEL) published by the American Association (AEA) is de facto standard for research literature in economics. JEL used to classify articles, dissertations, books, book reviews, and working papers EconLit, a database maintained AEA. Over time, it has evolved extended with over 850 subclasses. This paper reviews history development sys...

avian infectious bronchitis is an acute and highly contagious disease that mainly causes respiratory symptoms in poultry. a number of serotypes and variants of the viral agent with poor cross-protection are the major problem to achieve desired immunity from vaccination. the s1 subunit of s glycoprotein (spike) is the major determinant of ibv so that a minor change in amino acid sequence of this...