When to cite the whole book:

When the entire book has been written by the same set of authors, and the chapters have not been contributed by different authors, then you regard the entire book as a single source and cite the whole book. If you use three different chapters from the same book, it still only counts as one source - only one book.

Example:

Bach, S., Gilbert, R & Gilbert, P 1998, Masculinity goes to school, Allen & Unwin, St. Leonards, N.S.W.

Kamal, AA 2010, 1000 solved problems in modern physics, Springer, Berlin, viewed 3 April 2017, DOI:10.1007/978-3-642-04333-8.

When to cite the individual chapters:

If the book has been edited or compiled, and each chapter has its own authors, then you cite each chapter separately. If you use three different chapters, each chapter counts as a separate source.

Example:

Huth, E 2005, 'Fragments of participation in architecture', in P Blundell Jones & J Till (eds), Architecture and participation, Spon Press, London, pp. 141-8.

May, S & Donelson, R 2012, 'McKenzie Method', in S Dagenais & S Haldeman (eds), Evidence-based management of low back pain, Mosby, St Louis, pp. 122–133, viewed 6 March 2018, <https://www.sciencedirect.com/science/article/pii/B9780323072939000106>.