I need help solving a riddle

poetry has the name
science is not the game
the dream beneath the tree
line four, word one
the britannica will redirect you
to a second numbered page
take away all people that on earth do dwell
augment within is william
deduct beneath the cross of jesus
begin with r
then call the number you find
then point five two
before seven am

roses are red
hymnals are blue
in that song book
I found three clues
his name is william billings
the britannica you need
is in the library
pages lead you to a number
the number leads you back to pages
the number to call is a call number