Sentence Connectors. These are lexical items which connect two independent sentences/clauses, such as however, therefore, and moreover (they are often called "conjuncts").
Morrow (1989) suggests that cohesive ties marking relationships between ideas tend to be more explicitly marked through sentence connectors in formal academic discourse, and Ochs (1979) notes that sentence connectors are associated with planned rather than unplanned discourse.
Similar to sentence connectors, they explicitly indicate informational relations in texts.
Among all cohesive devices, grammatical cohesion in the form of sentence connectors, clause coordinators, and clause subordinators, as well as lexical cohesion in the form of pronoun referents, are used most often by the students, regardless of the medium in which the texts were produced.
As a matter of fact, four of the cohesive devices under investigation are used by all writers in both media: sentence connectors, clause coordinators, clause subordinators, and pronouns.
Sentence connectors, clause coordinators, and subordinators are very explicit means for establishing intra- and inter-sentential relations (Halliday & Hasan, 1976, 1990).