Apart from the main textbook, two other edited books on recent Australian national elections that are also free to download or read online are:
Anika Gauja, Marian Sawer and Marian Simms (eds.), Morrison's Miracle: The 2019 Australian Federal Election. Canberra: ANU Press, 2020. Available at: https://press.anu.edu.au/*****
Anika Gauja, Jennifer Curtin, Peter Chen and Juliet Pietsch (eds.), Double Disillusion: The 2016 Australian Federal Election. Canberra: ANU Press, 2018. Available at: https://press.anu.edu.au/*****
A useful introduction to Australian politics (including elections) that is also available free online is:
Nick Barry, Peter Chen, Yvonne Haigh, Sara C. Motta and Diana Perche (eds), Australian Politics and Policy (Junior Edition), Sydney: Sydney University Press, 2023. Available at: https://open.sydneyuniversitypress.com.au/*****