Select the pair of economists, who first gave the canons of taxation and public expenditure :

Adam Smith set out the four canons of taxation (equality, certainty, convenience and economy) in The Wealth of Nations (1776). G. Findlay Shirras later laid down the canons of public expenditure (benefit, economy, sanction and surplus) in his Science of Public Finance. Musgrave, Pigou, Ricardo, Prest and Ursula Hicks all wrote on public finance, but none of them first formulated these two sets of canons.