Cita APA (7th ed.)

B B S. (1990). Current level and trends… (1st edition.). B B S.

Cita Chicago (17th ed.)

B B S. Current Level and Trends…. 1st edition. Dhaka: B B S, 1990.

Cita MLA (9th ed.)

B B S. Current Level and Trends…. 1st edition. B B S, 1990.