Keeris, Willem, Ruben Langbroek, and Maarten Vermeulen. "Consequences of the break in the trend of the real estate cycle for investment analyses." In 18th Annual European Real Estate Society Conference. ERES: Conference. Eindhoven, the Netherlands, 2011.

Keeris, Willem, Ruben Langbroek, and Maarten Vermeulen. "Transform achieved results at national cultural bases to a pan-European standard." In 18th Annual European Real Estate Society Conference. ERES: Conference. Eindhoven, the Netherlands, 2011.

Keeris, Willem, and Ruben Langbroek. "Determination of the Value of Property Investments by Means of the Performance Potential and Risk-Return Improvement Ratio." In 14th Annual European Real Estate Society Conference. ERES: Conference. London, UK, 2007.

Keeris, Willem, and Philip W. Koppels. "The Diversification Capacity of Property Investments: Nothing is Sure." In 14th Annual European Real Estate Society Conference. ERES: Conference. London, UK, 2007.

Keeris, Willem, and Ruben Langbroek. "Measuring the Stability of Performance by Means of the Volatility Ratio." In 14th Annual European Real Estate Society Conference. ERES: Conference. London, UK, 2007.