On Doctoring MEDLINE searches, with reference librarian comments

The question was

"heart murmurs in infants and which have to be
surgically repared vs. not"

1 :  exp *Heart murmurs/         {590}
2 :  limit 1 to (newborn infant < birth to 1 month > or infant <         {79}
1 to 23 months >)
3 :  limit 2 to (human and english language)         {57}
4 :  Heart diseases/cn,su [Congenital, Surgery]         {2216}
5 :  3 and 4         {0}
6 :  2 and 4         {0}
7 :  Infant, newborn, diseases/cn,su [Congenital, Surgery]         {1252}
8 :  3 and 7         {0}
9 :  from 3 keep 1,4,6,19,42,47         {6}
10 :  from 3 keep 1,4-5,11,14,19,37,47,55         {9}
11 :  from 10 keep 1-9

Reference Librarian comments

I remember working with you on this interesting question. (I think I
was involved up to about set #3...).

I'd advise checking the "Explode" check-box almost always. If you
had done that with sets #4 and also #7, you would have found more and
better, probably. But it's clear that you're getting the hang of it.