> Why not year>1980 and year<1990 ?
As Ralph has pointed out (more times than I care to remember) this won't
always work when you have multiple occurences of an element as, for example,
suppose you have 1991 and 1975 as multiple years of publication. 1991 is
greater than 1990 and 1975 is less than 1980 so you get a hit, but neither
year is within the range.