1. A computer-implemented method of facilitating queries of a topic-based-source-specific search system, the search system being configured to collect information from predefined sources, wherein each of the predefined sources relates to a content topic and is associated with information items, the method being implemented by the search system that includes one or more processors executing one or more computer program instructions which, when executed by the one or more processors, cause the search system to perform the method, the method comprising: receiving, by the search system, a first portion of a query; identifying, by the search system, a first set of the predefined sources based on the first portion of the query; receiving, by the search system, a second portion of the query; identifying, by the search system, a second set of the predefined sources based on the second portion of the query; causing, by the search system, a suggested group of sources to search to be provided for presentation on a user interface, the suggested group of sources comprising at least the second set of the predefined sources; causing, by the search system, a query input component to be provided on a display of the user interface, wherein the query input component is configured to receive input; identifying, by the search system, a source set associated with a user, wherein the source set includes at least one source associated with the user; determining, by the search system, that the source set includes at least a first source of the suggested group of sources; determining, by the search system, that the source set does not include at least a second source of the suggested group of sources; causing, by the search system, one or more representations of options to modify the source set to be provided on a display of the user interface simultaneously with the query input component and the suggested group of sources, wherein the representations of the options to modify include a representation of an option to remove the first source from the source set based on the determination that the source set includes the first source and a representation of an option to add the second source to the source set based on the determination that the source set does not include the second source.