| Issue Date | Title | Author(s) | Publisher |
| 2011 | OpenAIREplus | Stanchev, Peter | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2014 | Open Research Data | Callaghan, Sarah | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2007 | Open Source Information Technologies Approach for Moddeling of Ankle-Foot Orthosis | Milusheva, Slavyana; Karastanev, Stefan; Toshev, Yuli | Institute of Information Theories and Applications FOI ITHEA |
| 2013 | An Open Virtual World for Professional Development | Stefanova, Eliza | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2007 | Operating Model of Knowledge Quantum Engineering for Decision-Making in Conditions of Indeterminacy | Molodykh, Liudmyla; Sirodzha, Igor | Institute of Information Theories and Applications FOI ITHEA |
| 1974 | The operating system of MID-2 | Bărnev, Petăr; Bărneva, Margarita; Petrov, Petăr | Bulgarian Academy of Sciences |
| 2006 | Operational Calculi for the Euler Operator | Dimovski, Ivan; Skórnik, Krystyna | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| Dec-2022 | Operational Calculus Approach for Obtaining Periodic and Mean-periodic Solutions of Linear Ordinary Differential Equations with Constant Coefficients | Dimovski, Ivan; Spiridonova, Margarita | Institute of Mathematics and Informatics at the Bulgarian Academy of Sciences |
| Feb-2010 | Operational Calculus Approach to Nonlocal Cauchy Problems | Dimovski, Ivan H.; Spiridonova, Margarita | Institute of Mathematics and Informatics at the Bulgarian Academy of Sciences |
| 2021 | Operational Conceptual Modeling in Building and Sustaining Technology Enhanced Learning Communities | Moumoutzis, Nektarios; Christoulakis, Marios; Sifakis, Yiannis; Christodoulakis, Stavros; Pavlov, Radoslav; Pavlova, Lilia | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 21-Nov-2022 | Operational Conceptual Modeling in Building and Sustaining Virtual Communities | Moumoutzis, Nektarios | - |
| 2009 | Operational Methods in the Environment of a Computer Algebra System | Spiridonova, Margarita | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2004 | Operational Rules for a Mixed Operator of the Erdélyi-Kober Type | Luchko, Yury | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2015 | Operator Algebras: an Introduction | Katavolos, Aristides | Institute of Mathematics and Informatics at the Bulgarian Academy of Sciences |
| 2003 | The Operators Aγ = γA + -γA for a Class of Nondissipative Operators A with a Limit of the Corresponding Correlation Function | Borisova, Galina | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 1995 | Operators Factoring through Banach Lattices and Ideal Norms | Reisner, Shlomo | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2012 | Operators with Polynomial Coefficients and Generalized Gelfand-Shilov Classes | Calvo, Daniela; De Donno, Giuseppe; Rodino, Luigi | Institute of Mathematics and Informatics Bulgarian Academy of Sciences |
| 2011 | Optimal Choice of a Firm in Conducting Auction | Baeva, Silvia; Nedeva, Cvetana | Union of Bulgarian Mathematicians |
| 2006 | Optimal Control of a Second Order Parabolic Heat Equation | Farag, Mahmoud; Al-Manthari, Mainouna | Institute of Information Theories and Applications FOI ITHEA |
| 2012 | Optimal Control of Heterogeneous Systems | Tsachev, Tsvetomir | Union of Bulgarian Mathematicians |
