While many studies have investigated information source selection in different user groups, few have explored the types of factors and how they influence resource selection. This study examines the types of information sources users select as well as the reasons behind their choices of information sources based on their actual searches. Thirty-one participants representing the general public with different demographic characteristics were recruited for the study. Data collected from diaries and questionnaires were analyzed by applying both qualitative and quantitative methods. The findings of this study show that electronic resources are the dominant information sources selected by participants. Seventeen types of factors including some new factors in relation to dimensions of tasks, characteristics of users, and attributes of sources were derived from the data. The results also indicated that multiple factors co-determined participants' selection of resources. Descriptive and statistical analysis of the data demonstrated that accessibility and familiarity of sources were correlated to information source usages, and the results suggested that participants utilized more print or human resources in accomplishing scholarly tasks while they were more dependent on electronic resources in achieving popular tasks.