A source is the material from which the content of constitutional law is derived. The syllabus identifies six heads — the constitution itself, statutes, secondary legislation, judicial decisions, non-legal rules (convention and custom), and books of authority. The hierarchy to remember for the examination: Constitution (as amended) → statutes → secondary legislation — all subject to judicial interpretation — supplemented by conventions, custom and scholarly literature, which stand outside the enforceable hierarchy but inside the living constitution.
Nepali reality check: Nepal's constitutional law cannot be built from the 2015 text alone. It is the product of seven constitutions (1948, 1951 interim, 1959, 1962, 1990, 2007 interim, 2015), of the movements that produced them (1950/51, 1990, 2006), and of a rich body of Supreme Court jurisprudence interpreting each — plus statutes, rules and conventions grown around them.