Gunasinghe, Liyanage & Nanda. (1986). Physics sound. Nugegoda: Open University.
Gunasinghe, Liyanage and Nanda. 1986. Physics sound. Nugegoda: Open University.
Gunasinghe, Liyanage and Nanda. (1986). Physics sound. Nugegoda: Open University.
Gunasinghe, Liyanage and Nanda. Physics sound. Nugegoda: Open University. 1986.