Concept: Institutional Repository is a digital platform used by an institution to collect, preserve and provide access to its intellectual output.
Step 1: Understand Institutional Repository.
An institutional repository may include theses, dissertations, research papers, reports, conference papers, working papers and other scholarly materials.
\[
IR = \text{Digital collection of institutional intellectual output}
\]
Step 2: Check research productivity.
Institutional repositories reflect the research productivity of an institution.
\[
B = \text{True}
\]
Step 3: Check open access support.
Institutional repositories generally support the open access model by making scholarly output freely accessible.
\[
D = \text{True}
\]
Step 4: Check non-English materials.
Repositories may include non-English materials depending on institutional policy.
\[
C = \text{True}
\]
Step 5: Identify the doubtful statement.
The statement that books are not included in the list of publications is not universally true because repositories may include books, book chapters or monographs depending on collection policy.
Therefore, the exact correct option is not clearly present among the given choices.