Mohamad Kassab Maya Daneva Olga Ormandjieva Towards an Early Software Effort Estimation Based on Functional and Non-Functional Requirements. 182-196 2009 IWSM/Mensura http://dx.doi.org/10.1007/978-3-642-05415-0_14 conf/iwsm/2009 db/conf/iwsm/iwsm2009.html#KassabDO09