concept (possibly invalid sql)

```sql
create table documents (
  doc_id integer primary key,
  content text
);


create table terms (
  term_id integer primary key,
  term_name text,
  parent_doc integer,
  foreign key (parent_doc) references documents (doc_id)
  );
  
create table citations (
  ref_id integer primary key,
  doc_id integer,
  term_id integer,
  foreign key (doc_id) references documents (doc_id),
  foreign key (term_id) references terms (term_id)
  );

create view document_graph as 
  select 
    doc_id, parents.doc_id 
  from 
    documents
  left join 
    citations on citations.doc_id = doc_id
  left join
    terms on terms.term_id = citations.term_id
  left join
    documents as parents on parents.doc_id = terms.doc_id;



```

can