Tibble/data.frame of works with additional columns:
append `citing`, `backward_count`, `cited_by`, `forward_count`, `connection`,
and `connection_count.` For each work/row, these counts are WITHIN one
data search, and so `forward_count` <= `cited_by_count`.
Consider the universe of all works linked to a set of starting works, (`oa_input = TRUE`)
for each work/row i:
- citing: works in the universe that i cites
- backward_count: number of works in the universe that i cites
- cited_by: works that i is cited by
- forward_count: number of works in the universe that i is cited by
- connection: works in the universe linked to i
- connection_count: number of works in the universe linked to i (degree of i)