1. and later adds "analysis will also have to account for the different speeds at which health affects the economy through various channels;; Weil;The conclusion from the literature is that residual productivity is by far the most significant source of income differences,1991
2. Eisenbahngüterverkehr
3. Much of the decline in mortality is attributable to medical science, but not to clinical practices per se;See Cutler & Miller,2005