- New results on the sum number of a certain class of graphs, Twenty second Australasian Conference on Combinatorial Mathematics and Combinatorial Computing, University of Technology Sydney, Australia, 1 – 5 July 1996.
- Sum graph labellings and related problems, Third International Conference on Combinatorial Mathematics and Combinatorial Computing, University of Melbourne, Australia, 30 June – 4 July 1997.
- Open problems in sum and integral sum graph labellings, Eighth Australasian Workshop on Combinatorial Algorithms, Noosa, Australia, 14 – 18 July 1997.
- Open problems in mod sum graphs, Eighth Australasian Workshop on Combinatorial Algorithms, Noosa, Australia, 14 – 18 July 1997.
- On magic labelings, Twenty fourth Australasian Conference on Combinatorial Mathematics and Combinatorial Computing, Northern Territory University, Darwin, Australia, 5 – 9 July 1999.
- New construction of digraphs with minimum diameter, Forty third Australian Mathematical Society Annual Conference join meeting with the American Mathematical Society, University of Melbourne, Australia, 12 – 16 July 1999.
- New construction of digraphs with minimum diameter, Summer 1999 Workshop on Graphs and Combinatorial Designs, University of Hawaii, USA, 31 July – 7 August 1999.
- Magic and antimagic labelings of graphs, Colloquium Series, Institute of Mathematical Sciences, Universiti Malaya, Malaysia, 26 June 2000
- Every generalized Petersen graph has a vertex-magic total labeling, Eleventh Australasian Workshop on Combinatorial Algorithms, Hunter Valley, Australia, 29 July – 1 August 2000.
- Diregularity of digraphs close to Moore bound, Konperensi Nasional Matematika X, ITB Bandung, Indonesia, 17 – 20 July 2000.
- On the monotonicity of minimum diameter with respect to order and maximum out-degree, Sixth Annual International Computing and Combinatorics Conference, Bondi Beach, Sydney, Australia, 26 – 28 July 2000.
- Diregularity of digraphs of out-degree three and order two less than Moore bound, Twelfth Australasian Workshop on Combinatorial Algorithms, Bandung, Indonesia, 14 – 17 July 2001.
- Construction of digraphs with minimum diameter, Konperensi Nasional Matematika XI, UM Malang, Indonesia, 22 – 25 July 2002.
- Construction techniques of large directed graphs, Indonesia Japan Conference on Computational Geometry and Graph Theory, ITB Bandung, Indonesia, 13 – 16 September 2003.
- Diregularity of digraphs, CGANT Research Mini Conference, University of Ballarat, Australia, 5 November 2004.
- Vertex magic and antimagic total labelings of union of two particular classes of graphs, International Workshop on Graph Labeling, Batu, Indonesia, 6 – 9 December 2004.
- Classification of Construction Techniques of Large Directed Graphs, International Conference on Applied Mathematics (ICAM05), ITB Bandung Indonesia, 22 – 26 Agustus 2005.
- Total vertex irregular labelings of wheels, fans, suns and friendship graphs, International Conference on Graph Theory and Information Security, ITB Bandung, Indonesia, 10 – 13 February 2007.
- Keteraturan graf berarah, Konferensi Nasional Matematika XIV, Universitas Sriwijaya, Palembang, Indonesia, 23 – 27 Juli 2008.
- Diregularity of large directed graphs, Asian Mathematical Conference, Kuala Lumpur, Malaysia, 22 – 26 Juni 2009.
- Classification of Construction Techniques of Large Directed Graphs, Seminar Teoria de Grafs, Universitat de Lleida, Lleida – Spanyol, 9 Desember 2009.
- Classification of Construction Techniques of Large Directed Graphs, Seminar Combinatorics, Graph Theory and Applications, Universitat Politecnica de Catalunya, Barcelona - Spanyol, 10 Desember 2009.
- On the total vertex irregularity strength of disconnected graphs, GraphMasters Workshop , ITB Bandung Indonesia, 18 – 19 Desember 2010.
