diff --git a/contrib/adsabs/src/java/org/apache/lucene/queryparser/flexible/aqp/builders/AqpAdsabsSubQueryProvider.java b/contrib/adsabs/src/java/org/apache/lucene/queryparser/flexible/aqp/builders/AqpAdsabsSubQueryProvider.java
index 70a190455..dd97515fd 100644
--- a/contrib/adsabs/src/java/org/apache/lucene/queryparser/flexible/aqp/builders/AqpAdsabsSubQueryProvider.java
+++ b/contrib/adsabs/src/java/org/apache/lucene/queryparser/flexible/aqp/builders/AqpAdsabsSubQueryProvider.java
@@ -1100,7 +1100,7 @@ public Query parse(FunctionQParser fp) throws SyntaxError {
 			}
 		});
 		
-	  // helper method; SOLR is not warming up caches when index is opened first time
+		// helper method; SOLR is not warming up caches when index is opened first time
 		// so we have to do it ourselves
 		parsers.put("warm_cache", new AqpSubqueryParserFull() {
 			@SuppressWarnings("unchecked")
@@ -1110,6 +1110,9 @@ public Query parse(FunctionQParser fp) throws SyntaxError {
 				@SuppressWarnings("rawtypes")
 				final CitationCache cache = (CitationCache) req.getSearcher().getCache("citations-cache");
 				if (!cache.isWarmingOrWarmed()) {
+					if (cache.size() > 0) {
+						return new MatchNoDocsQuery(); // we only allow it once (solr warms caches after first searcher was opened)
+					}
 					cache.warm(req.getSearcher(), cache);
 				}
 				return new MatchNoDocsQuery();
diff --git a/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderCollectorTopN.java b/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderCollectorTopN.java
index 4d66e1d82..4e76b57ba 100644
--- a/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderCollectorTopN.java
+++ b/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderCollectorTopN.java
@@ -57,7 +57,7 @@ public String toString() {
 
   @Override
   public boolean needsScores() {
-    return topCollector.needsScores();
+	  return this.topCollector.needsScores();
   }
 
   @Override
diff --git a/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderWeight.java b/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderWeight.java
index 616940f51..eab2fd6e4 100644
--- a/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderWeight.java
+++ b/contrib/adsabs/src/java/org/apache/lucene/search/SecondOrderWeight.java
@@ -38,7 +38,8 @@ public void extractTerms(Set<Term> terms) {
 
   @Override
   public Explanation explain(LeafReaderContext context, int doc) throws IOException {
-    return Explanation.match(0.0f, "nested, result of", innerWeight.explain(context, doc));
+	  Explanation innerExplanation = innerWeight.explain(context, doc);
+	  return Explanation.match(innerExplanation.getValue(), "nested, result of", innerExplanation);
   }